Top White House counter-terrorism adviser John Brennan
The top White House counter-terrorism adviser John Brennan will face a grilling soon at a Senate confirmation hearing to become CIA director.
The session comes as lawmakers were to receive secret papers setting out the rationale for drone strikes on Americans working with al-Qaida abroad.
Members of President Barack Obama's own Democratic party are concerned about Brennan's role in US drone policy, reports the BBC.
He was a top CIA official under President George W Bush.
Brennan, 57, is also likely to face questions about his position on harsh interrogation techniques, such as waterboarding, that were used by the CIA while he was a senior official there.
Correspondents say that despite these concerns there has been no suggestion that members of the Senate Select Committee on Intelligence object to Brennan's nomination.
He is expected to be confirmed by the panel and later by the full Senate.
A vote to confirm former Republican Nebraska Senator Chuck Hagel as secretary of defence has been delayed amid opposition from some member of his own party.
Brennan could face tough questions from Senator Ron Wyden, a Democratic member of the panel, who has vowed to press the nominee on drones.
Sen Wyden told MSNBC: "To make very clear, I am going to push for more declassification of these key kinds of [drone] programmes, and I think we can do that consistent with national security."
On the eve of Thursday's hearing, the committee released Brennan's answers to some preliminary questions.
Brennan said he "had significant concerns and personal objections" about extreme interrogation techniques used by the CIA, adding he was "aware of the program but did not play a role in its creation, execution, or oversight".
On drones, Brennan said no new legislation was necessary for the US to conduct operations against al-Qaeda anywhere in the world.
He said individuals were targeted for killing "on a case-by-case basis through a co-ordinated interagency process" involving intelligence, military, diplomatic and other agencies.