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Attorney general nominee Jeff Sessions and his allies, at the first confirmation hearing for President-elect Donald Trump’s Cabinet picks, mounted a full-scale response Tuesday to what they described as “character” attacks against him – decrying “false charges” about his past while offering assurances that if confirmed he would uphold and enforce the law.

On one of the most sensitive topics he could face if confirmed as attorney general, Sessions also publicly committed to recuse himself from any issues involving Hillary Clinton that were raised during the 2016 campaign.

“We can never have a political dispute turn into a criminal dispute,” the Alabama Republican senator said.

Sessions, under questioning from Senate Judiciary Committee Chairman Charles Grassley, R-Iowa, was trying to ease concerns about Trump’s suggestion during the campaign he might continue investigating his then-Democratic opponent, amid lingering questions over her email use and family foundation. Sessions, who campaigned for Trump, said the issue could place his objectivity in question as he vowed to recuse himself from any matters involving those controversies.

The hearing itself lasted all day and was interrupted repeatedly by protesters shouting epithets at the nominee, whom opponents have tried to paint as anti-immigrant.

Democrats also used the session to probe the nominee on his views on everything from abortion to marijuana policy –- and challenge him on the president-elect’s controversial comments and views. Sen. Patrick Leahy, D-Vt., at one point asked Sessions about leaked 2005 footage in which Trump was heard making lewd comments about grabbing women.

"Is grabbing a woman by her genitals without her consent sexual assault?" Leahy asked.

“Clearly” it is, Sessions answered.

Known for his staunch conservative stances on immigration and other issues, Sessions at times took a conciliatory tone. He pledged that even on laws he opposed, he would do his “dead-level best” to fairly enforce them. He indicated he accepts the legality of same-sex marriage, and also distanced himself from Trump’s campaign call to temporarily suspend Muslim immigration, saying he does not think Muslims as a religious group should be denied entry to the U.S.

But Sessions also fought back hard against what he described as a “caricature” of him -- first painted during his 1986 nomination for a federal judgeship that was derailed by accusations he had made racially insensitive comments as a prosecutor.

Sessions decried the “false charges” including suggestions he once sympathized with the KKK. He and his allies cited his past prosecution of Klansmen in countering the narrative, while Sessions denied another charge that he once called the NAACP “un-American.”

“I deeply understand the history of civil rights … and the horrendous impact that relentless and systemic discrimination and the denial of voting rights has had on our African-American brothers and sisters,” Sessions said, insisting he did not harbor racial animosities.

Sessions delivered testimony otherwise heavy on law-and-order themes, vowing to boost prosecutions and “confront” the crime epidemic.

Citing crime spikes in major cities like Chicago as well as the growing heroin epidemic, he said: “These trends cannot continue. It is a fundamental civil right to be safe in your home and your community.”

He vowed if confirmed to “systematically prosecute criminals who use guns in committing crimes” and go after cartels.

“It will be my priority to confront these crises vigorously, effectively, and immediately,” he said.

One of the two senators introducing him at Tuesday's hearing was moderate Republican Sen. Susan Collins of Maine, who vouched for her colleague’s character and swatted back the “character” attacks against him. Citing his prosecution of Klansmen and other incidents, she said, “These are not the actions of an individual who is motivated by racial animus.”

Grassley also praised Sessions’ record.  “We know him well,” said Grassley, R-Iowa. “… The members of this committee know him to be a leader who has served the people of Alabama and all Americans with integrity, with dedication and with courage.”

Protesters repeatedly tried to disrupt Tuesday's proceedings. As Sessions entered the hearing room, demonstrators in KKK costumes started shouting, and others held up signs that read, “Stand Against Xenophobia.” Others staged a prolonged disruption after Sessions voiced support for keeping the Guantanamo Bay detention camp open.

The hearing kicks off what is likely to be a contentious confirmation process for Trump’s Cabinet nominees.

John Kelly, a retired Marine general, had his hearing Tuesday afternoon before the Senate Homeland Security and Governmental Affairs Committee, while secretary of state pick Rex Tillerson heads to the Hill on Wednesday. Other key hearings have been delayed amid concerns from Democrats.

Democrats are expected to use the two days of hearings to challenge Sessions' commitment to civil rights, a chief priority of the Justice Department during the Obama administration, and other issues.

Sen. Dianne Feinstein, D-Calif., the committee’s top Democrat, offered words of caution in her opening remarks. She critiqued what she called Sessions’ “extremely conservative agenda,” citing his votes against the so-called DREAM Act and other policies Democrats backed.

But Republicans have expressed strong support and are expected to secure more than enough votes needed to confirm him, including from some Democrats in conservative-leaning states.

The Alabama lawmaker is known as one of the most staunchly conservative members of the Senate, and has already drawn opposition from at least two Democrats, New Jersey Sen. Cory Booker and Ohio Sen. Sherrod Brown.

In a dramatic turn, Booker -- one of three black senators -- said he will testify against Sessions on Wednesday, marking an apparently unprecedented move by a senator to testify against a colleague seeking a Cabinet post. In a statement, Booker accused Sessions of having a "concerning" record on civil rights and criminal justice reform and called his decision "a call to conscience." Booker has only been in the U.S. Senate since 2013, having previously served as Newark mayor.

If confirmed, Sessions, a four-term senator, would succeed outgoing Attorney General Loretta Lynch and would be in a position to dramatically reshape Justice Department priorities in the areas of civil rights, environmental enforcement and criminal justice.

Sessions was first elected to the Senate in 1996 and before that served as state attorney general and a United States attorney. He's been a reliably conservative voice in Congress, supporting government surveillance programs, objecting to the proposed closure of the Guantanamo Bay, Cuba, detention facility and opposing as too lenient a 2013 bipartisan immigration bill that included a pathway to citizenship for the estimated 11 million immigrants living in the U.S. illegally.

Civil rights advocates have rallied against his nomination, with protesters staging a sit-in last week at a Sessions office in Alabama and circulating letters opposed to his nomination. Advocacy groups have drawn attention to positions from Sessions they fear could weaken legal protections for immigrants, minority voters and gays, lesbians and transgender people.

Sessions' supporters have pointed to bipartisan work in the Senate and to supportive statements from some Democrats and even the son of a civil rights activist whom Sessions unsuccessfully prosecuted for voter fraud in Alabama.

The Associated Press contributed to this report.