WASHINGTON — President Barack Obama’s nominee for CIA director, John Brennan, said on Thursday he did not try to stop waterboarding, an interrogation technique that some consider torture, as he faced tough congressional questioning on that issue as well as security leaks and the use of drones to kill U.S. terrorism suspects.

Lawmakers grilled Brennan on controversial counterterrorism tactics used while he was a CIA official under President George W. Bush and in his role as counterterrorism adviser to Obama.

Brennan previously has said he objected to the harsh interrogation techniques while at the CIA.

But appearing before the Senate Intelligence Committee for his confirmation hearing, he acknowledged he did not attempt to stop the program, pointing out he was not in charge of it.

“I did not take steps to stop the CIA’s use of those techniques. I was not in the chain of command of that program,” Brennan told the hearing. “I had expressed my personal objections and views to some agency colleagues” about waterboarding, nudity and other techniques, he said.

“But I did not try to stop it, because it was something that was being done in a different part of the agency under the authority of others, and it was something that was directed by the administration at the time,” he said.

Democrats repeatedly questioned Brennan about the U.S. government’s use of armed unmanned aircraft known as drones. They pressed their demand that the White House provide them with more of the legal documents underpinning its position that Obama can order lethal strikes overseas on U.S. citizens suspected of terrorist activity.

Sen. Angus S. King, I-Maine, a member of the intelligence committee, also questioned Brennan about targeted drone strikes.

“The Fifth Amendment is pretty clear: no deprivation of life, liberty, or property without due process of law — and we’re depriving American citizens of their life when we target them with a drone attack … . I would like to suggest to you that you consider … a [Foreign Intelligence Surveillance Act] type court process when an American citizen is going to be targeted for a lethal strike; and I understand that you can’t have co-commanders in chief, but having the executive being the prosecutor, the judge, the jury, and the executioner all in one is very contrary to the traditions and laws of this country,” King said during the hearing.

On Wednesday, Obama directed the Justice Department to give congressional intelligence committees access to a classified memo on the topic.

The administration has insisted that only lawmakers be allowed access to the classified papers, which means the committee’s lawyers are unable to read them.

Sen. Dianne Feinstein, chairwoman of the intelligence committee, complained to Brennan that the committee’s staff had been banned from seeing the administration’s classified legal opinion.

Brennan, 57, said the limited access was necessary because of the “exceptional” nature of the issue. He has been central in overseeing drone policy in Obama’s administration.

Obama had wanted to pick Brennan for CIA director shortly after his 2008 election. But his chances were derailed mainly by liberal critics over the interrogation techniques used on terrorism suspects in the wake of the Sept. 11, 2001, attacks.

Thursday’s hearing was recessed shortly after Brennan started speaking because of protesters, who began yelling “Torture is always wrong” and “Stop the drones.”

Feinstein ordered the room cleared briefly.

Although there has been no groundswell of opposition to Brennan’s confirmation, some of the most intense questioning came from liberal Democrats, not the conservative Republicans who have raised the strongest objections to one of Obama’s other nominees — Chuck Hagel, his choice to lead the Pentagon.

Civil liberties groups have criticized the drone program as effectively a green light to assassinate Americans without due process in the courts under the U.S. Constitution.

Sen. Ron Wyden, a member of the intelligence committee who has pledged to press Brennan on drones, said in television interviews on Thursday he was encouraged by Obama’s decision to provide classified documents, but that more action is needed.

“To make very clear: I am going to push for more declassification of these key kinds of programs, and I think we can do that consistent with national security,” he told MSNBC. Asked on NBC if he still would block Brennan’s nomination, Wyden declined to give his position.

White House spokesman Jay Carney said Obama supports public discussion of the drone program, and that he has spoken about it publicly and would again.

“The president believes these are weighty matters and questions about how we move forward in our counterterrorism efforts are so important and the need to build a legal structure that guides those efforts, that survives in place beyond this administration,” he said.

The White House’s reluctance to release the classified information had angered lawmakers.

Some Republicans have praised the drone program.

“The drone program to me is a logical use of how you deal with an enemy combatant,” Sen. Lindsey Graham of South Carolina said on Wednesday.

Graham, one of the Republican senators most vocally opposed to Hagel’s appointment, said he is “totally supportive” of the administration’s rationale for using drones.

Brennan first surfaced as an Obama CIA nominee in 2008. He withdrew after human rights activists protested against his public statements about the agency’s use of what it calls “enhanced interrogation” techniques, including waterboarding, which a wide range of authorities regard as torture.

Brennan was expected to win confirmation from the panel and later the full Senate.