Brennan to face bipartisan scrutiny at confirmation hearing President Obama's nominee for CIA director could make Chuck Hagel's rocky confirmation hearing look like a cakewalk when he faces down lawmakers Thursday on Capitol Hill. John Brennan, currently the president's top counterterrorism adviser, will appear before the Senate Intelligence Committee on Thursday afternoon. Unlike Hagel, the Defense secretary nominee who endured withering criticism last week from Republicans, Brennan is facing complaints largely from members of the president's party. He's under fire for his support of the controversial drone program, an issue that flared this week with the leak of a Justice Department memo. And he faces continued questions about his views on Bush-era interrogation tactics. Republicans, meanwhile, have lingering questions for Brennan on his knowledge of high-profile leaks last year. On Wednesday, White House Press Secretary Jay Carney defended the nominee. "The president believes that John Brennan is uniquely qualified as a 25-year veteran of intelligence work, a 25-year veteran of the CIA, to lead that agency," Carney said. Mr. Brennan brings, I think, not only a vast amount of experience, but a significant perspective on the battles that we wage in this effort and the right way to conduct them. Carney said Obama wants the Senate to confirm him "expeditiously." Lawmakers may be reluctant to do so, with some threatening a "confrontation" over nominees in the midst of a debate over the drone program. On Monday, a bipartisan group of 11 senators wrote a letter to Obama asking for "any and all legal opinions" that describe the basis for the authority to "deliberately kill American citizens." Several of the authors of the drone letter sit on the committee that will grill Brennan on Thursday. In a not-so-subtle threat, they wrote: "The executive branch's cooperation on this matter will help avoid an unnecessary confrontation that could affect the Senate's consideration of nominees for national security positions." At the Senate Democrats' annual retreat Wednesday, Sen. Ron Wyden, D-Ore., further threatened to "pull out all the stops" to get the classified legal memos that justify the killing of Americans without judicial review. Brennan is described as the public face and architect of the targeted-killing program, which has expanded under Obama. The ACLU, a traditional supporter of Obama, is one of the program's chief critics. Under Brennan, the American cleric Anwar al-Awlaki, considered a top Al Qaeda operative, became the first American successfully targeted for death under the program. Two weeks later, his 16-year-old son was also killed in a drone strike, in which the teen was described as collateral damage. At the daily briefing, the White House was pressed to respond to concerns about the administration's authority. "I think it's fair to say that far fewer civilians lose their lives in an effort to go after senior leadership and Al Qaeda along the lines of what we are discussing here as opposed to an effort to invade a country with hundreds of thousands of troops and take cities and towns," Carney said. Renewed questions come after a Justice Department document surfaced describing the administration's drone-attack authority. The memo says it is legal for the U.S. government to authorize the killing of Americans overseas if they are suspected of being senior Al Qaeda leaders engaged in efforts to kill Americans. On this point, the Republican chairman of the House Intelligence Committee agreed. "When an individual has joined Al Qaeda -- the organization responsible for the murder of thousands of Americans -- and actively plots future attacks against U.S. citizens, soldiers and interests around the world, the U.S. government has both the authority and the obligation to defend the country against that threat," Rep. Mike Rogers, R-Mich., said in a statement. Brennan will also be pressed on his statements about the CIA's enhanced interrogation program -- which included waterboarding. In an interview with CBS News in 2007, Brennan defended the program as one that has produced information that's been "used against the real hardcore terrorists." Brennan has since apparently taken a position against the program and claimed he raised concerns while at the agency. A former deputy director at the agency could not confirm, in an interview with Fox News, that Brennan raised concerns with him. Still, the official, John E. McLaughlin, said he supports Brennan's confirmation and he should be taken at his word. "This was not a program that would normally be discussed between John and myself, but if he said he talked to colleagues about it, and expressed reservations, I believe him, because this is a very straight-forward, honest guy," McLaughlin told Fox News. Meanwhile, the head of the Senate Intelligence Committee, Democratic California Sen. Dianne Feinstein, has completed a 6,000-page classified report on the CIA program. Those familiar with its findings tell Fox News it concludes the agency lied about the program's effectiveness - a charge denied by those who ran the program. Brennan may be put in the tricky spot of explaining whether he agrees with the report's findings. As the intelligence committee holds the Brennan hearing, the Senate Armed Services Committee is still weighing how to proceed on the Hagel nomination. Some senators are urging a delay in the confirmation vote, as they seek additional answers to concerns about his background. The chairman of that committee said Thursday he would postpone a vote. Fox News' Catherine Herridge contributed to this report.