“I recognize that in our democracy, no one should just take my word that we’re doing things the right way,” the president said. “So, in the months ahead, I will continue to engage with Congress to ensure not only that our targeting, detention and prosecution of terrorists remains consistent with our laws and system of checks and balances, but that our efforts are even more transparent to the American people and to the world.”

The chairwoman of the Senate Intelligence Committee, Dianne Feinstein, Democrat of California, has long called for all Justice Department legal opinions on intelligence to go to the committee. But a spokesman said she did not believe the issue should block Mr. Brennan’s confirmation.

The votes of at least two other Democratic senators who feel strongly about greater access to the legal opinions, Ron Wyden of Oregon and Mark Udall of Colorado, are less certain.

“I still have a number of unanswered questions about the president’s authority to kill Americans who are deemed to be a threat to the United States,” Mr. Wyden said.

He said that he was “encouraged” by Mr. Obama’s promise of greater transparency in the State of the Union address but that “the administration has not yet lived up to that commitment.”

The administration is currently in discussions with Republican members of the Intelligence Committee about providing the trail of e-mails that were the basis of “talking points” from the intelligence agencies regarding the Sept. 11 attack in Benghazi, which killed the American ambassador to Libya, J. Christopher Stevens, and three other Americans. Such a concession would probably win at least some Republican votes for Mr. Brennan.

By most accounts, Mr. Brennan is likely to be confirmed as director of the C.I.A., in part because some human rights advocates who were once deeply skeptical about his record are now ambivalent.