It’s been nearly one month since the firing of FBI Director James Comey, invoking questions that President Donald Trump may have been unhappy with the handling of the probe into ties between Russia meddling in the 2016 election and Trump’s own campaign.

And on Thursday, Comey is set to testify in front of the Senate Intelligence Committee regarding his former department’s investigation. He is expected to testify that Trump asked him to drop the FBI’s investigation into Trump’s former national security advisor Michael Flynn and his ties to Russia.

Comey’s memos, that he was known to write after meetings, are also expected to come into play during the investigation. Chairman of the House Oversight Committee Jason Chaffetz, R-Utah, told Fox News that Comey should show the Senate those memos.

The White House said Monday that Trump will not use his executive privilege to block Comey’s upcoming testimony.

Read on for an overview of the Russia investigation and what’s led up to Comey’s testimony. 

Early problems

Before Trump ever took office, tens of thousands of emails from the Democratic National Committee and other officials connected to former Democratic presidential nominee Hillary Clinton were made public through WikiLeaks.

Those leaked emails — released in July 2016 ahead of the Democratic National Convention — purportedly showed the party favoring Clinton over Democratic challenger Bernie Sanders and led to the resignation of party chair Rep. Debbie Wasserman Schutlz.

But more than ousting Wasserman Schultz, intelligence officials concluded that those responsible for leaking the emails are connected to the Russian government. In its assessment of the hack, the CIA concluded that Russia intervened in the election in order to help Trump secure the presidency.

WHITE HOUSE DENIES TRUMP ASKED COMEY TO DROP INVESTIGATION OF FLYNN

Russia has staunchly denied involvement, but Russian President Vladmir Putin lauded the leaks as “important” because they made the information public.

Before he handed over the White House to Trump, former President Barack Obama sanctioned Russia for its alleged involvement in the election — a move that would eventually come back to dismantle one of Trump’s own senior aides.

Flynn’s fall

Michael Flynn’s tenure as Trump’s national security adviser was short but rife with controversy, and it still bedevils the Trump administration. But Flynn didn’t come without a warning.

Only a few days after the November election, Obama reportedly met with Trump to share his concerns about Flynn, a retired lieutenant general. Flynn had served under Obama as head of military intelligence until he was fired in 2014 following reports of insubordination and questionable management style.

Still, Trump ignored Obama’s apparent apprehensions and selected Flynn as his national security adviser.

Not even a month after Flynn was sworn in, Trump was already accepting his resignation.

PUTIN OFFERS TO SETTLE CONTROVERSY OVER WHAT INTEL TRUMP GAVE RUSSIAN OFFICIALS                 

As Obama issued sanctions on Russia for its involvement in the presidential election, Flynn reportedly was on the phone with the Russian ambassador to discuss the move. Flynn ultimately denied having spoken to the ambassador; when intelligence officials revealed proof of the discussions, Flynn said he didn’t remember speaking on that topic.

Flynn resigned under harsh scrutiny for misleading the administration, including Vice President Mike Pence, about his ties to and conversations with Russian officials.

Flynn was subpoenaed on May 10 by the Senate Intelligence Committee, which is looking into Russia’s influence on the 2016 election. Flynn is also under investigation by other congressional committees and the Pentagon’s inspector general regarding his Russian contacts and dealings.

EX-FBI DIRECTOR JAMES COMEY STATEMENT FOR THE RECORD TO SENATE INTEL COMMITTEE

Flynn initially invoked his Fifth Amendment right against self-incrimination. But Flynn’s attorneys eventually conceded to the Senate Intelligence Committee and announced that Flynn would begin to turn over documents and records in response to a subpoena by June 6. 

More connections

Flynn was not the only Trump associate who had contacts with Russia, The New York Times reported in February.

Law enforcement and intelligence officials allegedly intercepted communications from Trump associates and campaign aides, including former campaign manager Paul Manafort, repeatedly in the year leading up to the election, according to the Times.

The Times reported that Manafort has done business in Russia — something that is not unusual for businessmen — and he was not charged with a crime.

Firing Comey

Trump sacked Comey on May 9, less than two months after Comey publicly proclaimed that the FBI was investigating ties between Russia’s involvement in the presidential election and Trump’s own campaign.

“I have been authorized by the Department of Justice to confirm that the FBI, as part of our counterintelligence mission, is investigating the Russian government’s efforts to interfere in the 2016 presidential election and that includes investigating the nature of any links between individuals associated with the Trump campaign and the Russian government and whether there was any coordination between the campaign and Russia’s efforts,” Comey said during a House Intelligence Committee hearing on March 20.

MCMASTER BLAMES LEAKERS FOR PUTTING NATIONAL SECURITY AT RISK 

“As with any counterintelligence investigation, this will also include an assessment of whether any crimes were committed,” he added.

The White House maintained Comey was relieved from his duties due to his handling of the investigation into Clinton’s private email server during her tenure as secretary of state.

Trump told NBC News in an interview following the firing that he never attempted to pressure Comey into dropping the investigation. Instead, Trump said, he would like to find out what role Russia played in the election.

"As far as I'm concerned, I want that thing to be absolutely done properly," Trump told NBC. "Maybe I'll expand that, you know, lengthen the time [of the Russia probe] because it should be over with, in my opinion, should have been over with a long time ago [because] all it is, is an excuse but I said to myself, I might even lengthen out the investigation, but I have to do the right thing for the American people."

He also denied any “collusion” between his campaign and the Russians during that interview.

While the FBI remains mum on specific details into the investigation — as is the norm — Trump claimed in his letter firing Comey that he was told multiple times by the former director that he is not under investigation.

“While I greatly appreciate you informing me, on three separate occasions, that I am not under investigation, I nevertheless concur with the judgment of the Department of Justice that you are not able to effectively lead the Bureau,” Trump said.

CONGRESSIONAL DEMS CALL FOR TRUMP'S IMPEACHMENT

He has also dismissed the allegations of ties between his officials and Russia on Twitter, calling it a “hoax” and “taxpayer funded charade.”

But Democrats and critics of the Trump administration called into question the reasoning behind Comey’s termination. Democratic Sens. Bob Casey and Patrick Leahy even labeled the situation “Nixonian,” drawing comparisons between Comey’s dismissal and former President Richard Nixon’s firing of special prosecutor Archibald Cox during the Watergate scandal.

Russian intelligence

In the wake of Comey’s dismissal, the Trump administration was rocked with reports of Trump’s own controversial dealings with the former FBI director and Russian officials in the Oval Office.

On May 15, the Washington Post reported that Trump shared classified information regarding ISIS threats with Russian officials.

The information Trump reportedly shared with Russian Foreign Minister Sergei Lavrov and Ambassador Sergey Kislyak was given to the U.S. by Israel and was not meant to be shared, the Washington Post reported.

“As President I wanted to share with Russia (at an openly scheduled meeting) which I have the absolute right to do, facts pertaining to terrorism and airline flight safety,” Trump tweeted the morning following the report.

“Humanitarian reasons, plus I want Russia to greatly step up their fight against ISIS and terrorism,” he added.

TRUMP AGENDA AT RISK AFTER SERIES OF CONTROVERSIES

National Security Adviser Gen. H.R. McMaster pushed back on the report, saying Trump’s conversations were “wholly appropriate.” McMaster used that phrase — “wholly appropriate” — nine times during a briefing with reporters.

Russian President Vladimir Putin also denied that Trump shared any secrets with Lavrov and promised to turn over his records of the meeting to Congress.

Trump met with Lavrov and Kislyak the day after he fired Comey — again causing an outcry among Democrats about the optics.

On May 25, reports claimed that Trump's son-in-law and top adviser Jared Kushner was under FBI scrutiny.

Kushner, who is married to Trump’s daughter Ivanka, may possess substantial information relevant to the Russian investigation, officials told NBC.

Kushner, who held meetings in December 2016 with Kislyak and a banker from Moscow, is being probed due to the extent and nature of his interactions with the Russians, people familiar with the investigation told The Washington Post.

The information Kushner may possess, however, doesn’t mean that officials necessarily suspect him of a crime or intend to charge him.

Protecting Flynn

The New York Times also reported that Comey kept a paper trail of memos detailing his conversations with Trump. One of those memos, according to the Times, claims that Trump asked Comey to drop the FBI’s investigation into former National Security Adviser Michael Flynn.  

“I hope you can see your way clear to letting this go, to letting Flynn go,” Trump reportedly told Comey. “He is a good guy. I hope you can let this go.”

The memo was reportedly written after Comey met with Trump in the Oval Office on Feb. 14 — the day after Flynn resigned.

The White House strongly denied the Times’ report, saying Trump “never asked Mr. Comey or anyone else to end any investigation,” including Flynn's.

“This is not a truthful or accurate portrayal of the conversation between the President and Mr. Comey,” the White House said.

The report furthered stoked cries from Democrats and critics of the Trump administration that the Republican president fired Comey over the FBI’s investigation into Russia’s influence in the election — and potential ties to Trump’s campaign.

GOP POLS VOICE CONCERN ON TRUMP 'DRAMA'

“Concerns about our national security, the rule of law, and the independence of our nation’s highest law enforcement agencies are mounting,” Senate Minority Leader Chuck Schumer, D-N.Y., said from the Senate floor. “The country is being tested in unprecedented ways.”

Sen. Dick Durbin, D-Ill., called into question if Trump’s request of Comey to “[let] Flynn go” could be considered “obstruction of justice.”

Comey testimony

Comey testified before the Senate Intelligence Committee on June 8 and accused Trump trying to “defame” him.

“The administration then chose to defame me and more importantly the FBI by saying that the organization was in disarray,” Comey said. “That it was poorly led. That the workforce had lost confidence in its leader. Those were lies, plain and simple.”

Comey also said he was concerned about the “shifting explanations” that came from the White House in regards to his firing.

Comey confirmed during the hearing that he did reassure Trump that he was not under investigation by the FBI during its probe.

But he also declined to say whether he thinks the Trump campaign did collude with the Russians in the election. When asked by Sen. Tom Cotton, R-Ark., about his opinion, Comey said he couldn’t answer in “an open setting.”

“I am not trying to suggest by my answer something nefarious,” he said.

On Trump’s request to “let go” of the FBI’s investigation of Flynn, Comey said he didn’t believe Trump’s words to be an “order” but took them as “direction.”

Comey said that he believes he was fired over the Russian investigation.

“I know I was fired because of something about the way I was conducting the Russia investigation was in some way putting pressure on him, in some way irritating him, and he decided to fire me because of that,” Comey testified.

Comey also admitted that he gave memos that he kept about his interactions with Trump to a friend in order for that friend to leak them to the media.

"I asked a friend of mine to share the content of the memo with a reporter—I thought that might prompt the appointment of special counsel,” Comey told lawmakers.

The New York Times published a report on May 16 that revealed a Comey memo detailed how Trump supposedly asked him to end the investigation of Flynn. Comey said in a congressional testimony on May 3 that he was never an anonymous source for media reports regarding the Clinton email investigation or the Russian investigation.

He said he kept the memos about his interactions with the president – the first time he did so with a president – because he felt as though Trump would lie about their conversations.

In prepared statements released the day before the hearing, Comey described a one-on-one dinner with Trump, during which Trump told the FBI chief his expectations. “I need loyalty, I expect loyalty,” Trump allegedly said.

"I didn't move, speak, or change my facial expression in any way during the awkward silence that followed," Comey said of the dinner when Trump requested loyalty.

Marc Kasowitz, Trump’s personal lawyer, said Thursday that Comey’s testimony proved Trump’s innocence in the Russia situation.

“Mr. Comey’s testimony also makes clear that the president never sought to impede the investigation into attempted Russian interference in the 2016 election,” Kasowitz said.

But Kasowitz did criticize Comey as he “admitted that he unilaterally and surreptitiously made unauthorized disclosures to the press of privileged communications with the president.”

By Thursday afternoon, Trump himself had not commented or tweeted on Comey’s testimony.

Lawmakers' response

In the wake of reports regarding Trump’s potential influence in the FBI’s investigation, Democrats have ramped up their calls for a special prosecutor to take over the probe.

Sen. Tom Udall, D-N.M., argued in a speech from the Senate floor that Democrats could withhold appointing Comey’s replacement until such a prosecutor is secured.

“A special counsel must be appointed before we consider a new nominee for FBI director, and that nominee needs to be closely scrutinized by the Senate,” Udall said. “This person will be responsible for restoring Americans’ confidence in the FBI and ensuring that he or she does not pledge loyalty to the president but pledges loyalty to the Constitution.”

Multiple Republicans have echoed the call for a special prosecutor, including Rep. Adam Kinzinger, R-Ill.

“I think it’s time that we do whatever is necessary that when this is over we give the American people the confidence that justice either way, either way it goes, has been served,” Kinzinger said during a CNN interview on May 17.

PAUL RYAN WARNS AGAINST RUSHING TO JUDGMENT ON COMEY MEMO

Rep. Steve Knight, R-Calif., also called for a special prosecutor and said he supports “any efforts” from the House Intelligence Committee to appoint such a person.

“It is time for an investigation of Russia’s intervention in the U.S. election. There is too much at stake at home and abroad to not take this step,” Knight said in a statement. “There is so much conflicting information from many sources; Americans deserve the opportunity to learn the truth.”

Former FBI Director Robert Mueller was appointed by the Justice Department on May 17 to oversee the federal investigation into Russia’s influence on the election. 

But other Democrats want to take it a step further and impeach the president, as Fox News reported. Rep. Al Green, D-Texas, called for Trump’s impeachment in a May 16 statement as “no one is above the law.”

“President Trump has committed an act for which he should be charged by the U.S. House of Representatives,” Green said. “The act is the obstruction of a lawful investigation of the President’s campaign ties to Russian influence in his 2016 Presidential Election.”

Rep. Jared Huffman, D-Calif., remarked a few days earlier on Twitter that Trump’s impeachment could happen should a “handful of Republicans in Congress join Dems to put country above party.”

It could also happen, Huffman continued, should Democrats win back a majority in the House in 2019.