In opening remarks, Sessions said the Attorney General "must be willing to tell the president 'no' if he overreaches"
Republican Senator Jeff Sessions faced interruptions at his confirmation hearing for US Attorney General.
Protesters were forcibly removed from the Senate Judiciary Committee hearing, following chants of "No Trump, No KKK, No Fascist USA". Some were dressed in KKK robes and another held a sign that said "Support Civil Rights, Stop Sessions."
Mr Sessions became the first sitting senator to endorse Donald Trump for the presidency in early 2016 and has remained a close advisor on issues such as immigration.
Democratic Senator Diane Feinstein said the Senate Judiciary Committee has received letters from 400 civil rights organizations opposing his confirmation to the country's top law enforcement post.
"This job requires service to the people and the law, not the president," Feinstein said.
Sessions has been sharply criticized by civil rights advocates for prosecuting three black leaders in 1985 on voter fraud charges. He has also been accused of making racially insensitive remarks, including one in which he said he thought the Ku Klux Klan was okay until he learned its members smoked marijuana. Sessions and some others have said he was cracking a joke.
However, Sessions forcefully rebutted allegations that he had once harbored sympathies for racist groups and had condemned civil rights advocates.
"These are damnably false charges," Sessions said, straying from his prepared statement.
The senator promised he will crack down on illegal immigration, gun violence and the "scourge of radical Islamic terrorism" in prepared remarks at the opening of his hearing.
He also warned of a country struggling to combat illegal drugs flowing across its border, spikes in violent crime and low morale among the police.
Jeff Sessions: "I do not support the idea that Muslims as a religious group should be denied admission to the United States."— Del Quentin Wilber (@DelWilber) January 10, 2017
During the Presidential campaign, Sessions and Trump called for Democratic nominee Hillary Clinton to be investigated and prosecuted for her use of a private email server, despite determinations by the FBI and Justice Department that her actions did not warrant charges. Since his election, Trump has said he did not support such an investigation or prosecution.
Sessions said he had made comments during the "contentious" campaign about Clinton's use of the email server and her family's charitable foundation that could place his objectivity in question.
"I believe the proper thing for me to do would be to recuse myself from any questions involving those kind of investigations that involve Secretary Hillary Clinton," Sessions told senators on the Judiciary Committee.
The President-elect had described his cabinet picks as "all at the highest level" and predicted on Monday that all of his candidates would win Senate confirmation.
But politicians from both parties will pore over the background material, including billionaires whose personal financial dealings have never faced public scrutiny before.
A similar hearing for retired Marine Corps General John Kelly - chosen to be Homeland Security secretary - is also set to take place on Tuesday.
Seven other cabinet picks will face hearings this week, with some likely to have to negotiate difficult questions over business dealings, political alliances and civil rights records.
Other nominees due to be heard include James Mattis for Defence Secretary, Rex Tillerson for Secretary of State and most recently announced Jared Kushner for Senior Advisor.