Attorney General Jeff Sessions told senators he won't answer questions about his conversations with President Donald Trump over the firing of FBI Director James Comey.

"I can neither assert executive privilege, nor can I disclose today the content of my confidential conversations with the president," Sessions told the Senate Judiciary Committee Wednesday. "A president is entitled to have private, confidential communications with his Cabinet officials. Until such time as the president makes a decision with respect to this privilege, I cannot waive that privilege myself or otherwise compromise his ability to assert it."

Committee members of both parties signaled at the start of an oversight hearing that they would press Sessions on Comey's firing in May and the attorney general's decision to recuse himself from the investigation into Russian meddling in last year's presidential campaign.

"The American people have a right to know why he was fired, especially with so many high-profile issues going on, including the investigation into Russian interference with the 2016 election," Sen. Chuck Grassley, the committee's Republican chairman, said.

Sen. Dianne Feinstein, the panel's top Democrat, said clear answers are needed given the shifting story on the reasons for Comey's firing. Trump first said he did so on the recommendation of Sessions and Deputy Attorney General Rod Rosenstein and later that it was because of "the Russia thing."

"It's important, I believe, to understand what role you had in this process, including conversations with the president and others in the White House," Feinstein said.

She said senators "expected answers or a valid claim of executive privilege by the president."