Barr is virtually assured of approval in the Senate, where Trump's Republican Party holds a majority.
Democrats on the committee said they were concerned that Barr's expansive views of presidential power, as outlined in his memo, would lead him to suppress parts of Mueller's report that address whether Trump tried to obstruct the investigation.
Barr also said he will not allow any interference with the Mueller probe, adding that he will release the special counsel's final report as much as he can under the law.
"We need an attorney general who can assure the Senate and the public that he will stand up to a president who believes the Justice Department exists to do his personal bidding and to protect his personal interests", Schumer said in a tweet.
A practicing Catholic and a member of the Knights of Columbus, Barr said in his confirmation hearings that he did not believe his faith would hinder his ability to serve as an effective attorney general. "I don't know what Bob Mueller is writing", Barr said at his hearing last month.
Previous year he sent an unsolicited legal opinion to the Justice Department and White House arguing that Mueller had no grounds to investigate Trump for obstruction of justice based on the firing of Federal Bureau of Investigation director James Comey in May 2017. The Judiciary panel is set to vote on Barr's nomination Tuesday.
But Democrats said Thursday that Barr's comments did not go far enough to reassure them.
Sen. Richard J. Durbin (D-Ill.) said he felt Barr was a "good person" and likened him to Jim Mattis - Trump's former defense secretary, who had a reputation for being independent and resigned from the administration amid disagreements with the president.