The Senate Intelligence Committee votes Tuesday on whether John Brennan should head the CIA, the last of three critical national intelligence posts to be filled in President Barack Obama's cabinet.
After John Kerry was named secretary of state and Chuck Hagel survived a bruising battle to be the new Pentagon chief, confirmation of Brennan to replace David Petraeus as head of the spy agency is key for the president, whose CIA pick has been subjected a two-month confirmation process.
But some US lawmakers say that outstanding questions remain about Brennan's nomination, with Republicans acknowledging that they hope to extract more information from the White House about its secret drone program and the attack on US diplomats September 11 in Benghazi, Libya.
Tuesday's vote will take place in a closed-door committee hearing at 2:30 pm (1930 GMT), aides said, and Senate Majority Leader Harry Reid has made clear that, barring any hiccups in committee, he wants a full Senate floor vote this week.
Brennan, 57, is a 25-year veteran of the Central Intelligence Agency. For the past four years he has worked in the White House as Obama's chief counter-terrorism expert, and helped orchestrate the secret US program of targeted killings by unmanned aerial drones.
The drone program, and particularly the guidelines on killing American citizens suspected of involvement in terrorism, was a particularly controversial issue during Brennan's confirmation hearing last month.
Committee chair Dianne Feinstein said Tuesday that the White House provided additional materials to senators in recent days, including documentation that may have been used to justify US drone strike policy.
"I have reached an agreement with the White House to provide the committee access to all OLC (Office of Legal Counsel) opinions related to the targeted killing of Americans in a way that allows members to fulfill their oversight responsibilities," she said in a statement.
On Monday, Republican Senators John McCain, Lindsey Graham and Kelly Ayotte released a statement highlighting 10 questions that remained unanswered, including several addressing the degree to which the president was made aware of attacks on numerous foreign missions in Libya, culminating with the attack that killed four Americans including ambassador Christopher Stevens.
"I think John and I are hell-bent on making sure the American people understand this debacle called Benghazi," Graham, a close McCain ally, said Sunday as the two appeared on CBS.
McCain said he believed he deserved responses from Brennan and the White House, but he stopped short of saying he would try to put a hold on the nomination until he gets answers.