Longtime Democratic Pennsylvania Sen. Bob Casey voted to kill the impeachment trial of Homeland Security Secretary Alejandro Mayorkas last week, but has a long track record of supporting impeachment proceedings when former President Trump was in the hot seat with Democrats. 

The Senate voted against two articles of impeachment Mayorkas faced last week, including one that charged Mayorkas with "willful and systemic refusal to comply" regarding immigration law, and a second article that charged him with a "breach of trust" after saying the border was secure. The Senate voted 51-48 and 51-49 against the articles. 

The votes were largely along party lines, with Sen. Lisa Murkowski of Alaska serving as the only Republican who voted "present" when asked about dismissing the first article, and voted against dismissing the second article. 

Republicans were pushing for a trial of Mayorkas for "willfully" refusing to enforce immigration laws, while millions of illegal immigrants have poured across the border into the U.S. since he was sworn in as the Biden administration’s secretary of Homeland Security in 2021. 

GOP PREPS ATTACKS ON VULNERABLE DEM SENATORS OVER MAYORKAS IMPEACHMENT TRIAL DISMISSAL

Pennsylvania Democratic Sen. Bob Casey

Sen. Bob Casey Jr. leaves the Capitol after a vote on April 18, 2023. (Bill Clark/CQ-Roll Call, Inc via Getty Images)

Casey was among the Democrats who voted to kill the impeachment trial of Mayorkas, but had largely been tight-lipped ahead of the vote. Fox News Digital reported last week ahead of the Senate vote that Casey had not yet revealed his plans, while Politico reported on April 10 that Casey "did not directly answer a question on whether or not he’d support a motion to dismiss the trial."

He did tell the outlet at the time that "the Senate should be spending time passing the bipartisan border deal" and that he has "no doubt at all" that Republicans would use the impeachment trial against him and other vulnerable Senate Democrats ahead of the election. 

DHS chief Alejandro Mayorkas testifies on Capitol Hill

Homeland Security Secretary Alejandro Mayorkas speaks on Capitol Hill, on April 10. (AP/Mark Schiefelbein)

Senate Democrats quashing impeachment proceedings against Mayorkas was historically significant, as he is still serving in his role in public office. It marks a first for an impeachment trial to be dismissed, tabled or effectively tossed without the accused official first exiting their role, Fox Digital previously reported. 

"The Senate has no constitutional authority to rule that the articles approved by the House do not state impeachable offenses," Andrew McCarthy, a former chief assistant United States attorney in the Southern District of New York and a senior fellow at the National Review Institute, said last week. 

McCarthy added that the House has the sole power to determine impeachable offenses, and the Senate deeming the articles of impeachment unconstitutional and killing the potential trial, "essentially nullifies the House’s important role in the impeachment process." 

REPUBLICANS PREDICT DEMS TO PAY 'HEAVY PRICE' IN ELECTION AFTER MAYORKAS IMPEACHMENT BID FAILS

The Senate voting against carrying through with the trial of Mayorkas comes after Casey repeatedly publicly supported impeachment proceedings against Trump when he was president.

"There can be no justice without accountability for those involved in the insurrection against the federal government. As a Nation, we cannot advance our shared democratic values without consequences for those who have betrayed those values. Those who stormed the Capitol should face charges. President Trump should be impeached and removed from office because he betrayed his oath to the Constitution and incited a mob to violence," Casey said in 2021, following protesters breaching the U.S. Capitol on Jan. 6 of that year. 

‘CONSTITUTIONAL AUTHORITY’ OF SENATE DEMS QUASHING MAYORKAS IMPEACHMENT TRIAL QUESTIONED BY EXPERTS

In 2020, when Democrats accused Trump of soliciting foreign interference in the 2020 election, Casey said, "Americans deserve a fair trial" when touting articles of impeachment against the 45th president. 

"Soon the Senate will take a critical vote on whether we should hear from relevant witnesses like John Bolton. Americans deserve a fair trial. Anything less is a cover-up," he said on X at the time.

That same month, he also called for "answers, under oath, in full view of the American people," as part of Trump’s first impeachment.

He added in 2019 of the Trump impeachment that failing to pursue proceedings against Trump would be "an insult to our Constitution and to our values."

PENNSYLVANIA POLICE SLAM LONGTIME DEM SEN. CASEY 'ALIGNING' HIMSELF WITH DEFUND THE POLICE GROUP: 'DANGEROUS'

Former President Trump with right fist raised, leaving Trump Tower

Former President Trump exits Trump Tower in New York City, Monday, April 15, 2024. (Probe-Media for Fox News Digital)

"Our Constitution indicates that impeachment is for ‘treason, bribery, or other high Crimes and Misdemeanors.’ A failure by Congress to pursue impeachment in the face of grave offenses by the President is an insult to our Constitution and to our values."

Trump was ultimately impeached twice, an historical first for a president, and acquitted on all counts by the Senate. 

Casey has served in the Senate since 2007, and is anticipated to have one of the most closely watched elections this year as he gears up for a campaign against anticipated Republican challenger Dave McCormick. Pennsylvania holds its primaries Tuesday, which will solidify the expected race between Casey and McCormick

REPUBLICAN DAVE MCCORMICK LAUNCHES BID FOR VULNERABLE SENATE SEAT IN BATTLEGROUND STATE

Dave McCormick, Republican candidate for U.S. Senate from Pennsylvania

Republican Senate candidate Dave McCormick is joined by state Auditor General Timothy DeFoor and state Treasurer Stacy Garrity on Sept. 30, 2023, in Harrisburg, Pennsylvania. (Dave McCormick campaign )

The Pennsylvania Democrat and fellow vulnerable Senate members have now come under greater focus from the Republican Party following the Mayorkas vote, including the National Republican Senatorial Committee (NRSC) previously telling Fox Digital that their votes against proceeding with the trial will become a focal point of election season. 

"Joe Biden’s wide open border is going to be a top issue for voters headed into November," NRSC spokesperson Maggie Abboud told Fox News Digital in a statement last week. 

BATTLEGROUND STATE DEM DISTANCES HIMSELF FROM DEFUND MOVEMENT, BUT POLITICAL RECORD SHOWS DIFFERENT STORY

Sen. Bob Casey gesturing with right hand at podium

Sen. Bob Casey speaks before President Biden about his infrastructure agenda on Feb. 3, 2023, in Philadelphia. (AP Photo/Patrick Semansky, File)

"You can bet we are going to highlight Senate Democrats’ refusal to hold Joe Biden’s DHS Secretary accountable on the campaign trail, in advertising, and in every other way possible," she continued. 

Fox News Digital reached out to the Casey campaign for comment on the Mayorkas vote and his previous remarks on Trump’s impeachment proceedings, and were directed to the Senate office. The Senate office did not immediately respond to the inquiry.  

Migrants storm the gate at an El Paso border crossing

A group of migrants attempting to enter the U.S. illegally rush the border on March 21, 2024, knocking down a Texas National Guardsmen before they are halted at the border wall. (James Breeden for New York Post / Mega)

"Together, Casey, Biden and Mayorkas have enabled drug cartels to flood Pennsylvania communities with deadly drugs like fentanyl," Elizabeth Gregory, a spokesperson for McCormick, said last week.

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Immigration has become a top concern for voters ahead of November, alongside other concerns such as inflation, the economy and crime. Nearly 7.3 million migrants entered the U.S. between President Biden taking office and February 2024, a Fox News Digital analysis previously reported. The figure is more than the population of 36 individual states. 

Get the latest updates from the 2024 campaign trail, exclusive interviews and more at our Fox News Digital election hub.

Fox News Digital's Julia Johnson contributed to this report.