US Attorney General Jeff Sessions is expecting sharp questions from his former Senate colleagues about his ties with Russia.
The public evidence before the Senate Intelligence committee should yield Mr Sessions' most extensive comments to date on his role in the firing of James Comey, his Russian contacts during the campaign and his decision to step aside from an investigation into possible ties between Moscow and associates of President Donald Trump.
The questions have dogged his tenure as attorney general and led him three months ago to recuse himself from the Russia probe.
Senators for weeks have demanded answers from Mr Sessions, particularly about meetings he had last summer and autumn with the Russian ambassador to the United States.
Those calls have escalated since fired FBI director Mr Comey cryptically told senators last week that the bureau had expected Mr Sessions to recuse himself weeks before he did from the investigation into contacts between Trump campaign associates and Russia during the 2016 presidential election.
Mr Sessions, a close campaign adviser to Mr Trump and the first senator to endorse him, stepped aside from the investigation in early March after acknowledging he had spoken twice in the months before the election with the Russian ambassador. He said at his January confirmation hearing that he had not met with Russians during the campaign.
Since then, questions have been raised about a possible third meeting at a Washington hotel, though the Justice Department has said that did not happen.
Mr Sessions on Saturday said he would appear before the intelligence committee, which has been doing its own investigation into Russian contacts with the Trump campaign.
There had been some question as to whether the hearing would be open to the public, but the Justice Department said he requested it be because he "believes it is important for the American people to hear the truth directly from him".
Mr Sessions is likely to be asked about his conversations with Ambassador Sergey Kislyak and whether there were more encounters that should have been made public.
And he can expect questions about his involvement in Mr Comey's May 9 firing, the circumstances surrounding his decision to recuse himself from the FBI's investigation, and whether any of his actions - such as interviewing candidates for the FBI director position or meeting with Mr Trump about Mr Comey - violated his recusal pledge.
As attorney general, Mr Sessions is unlikely to answer in detail questions about conversations he has had with Mr Trump. National Security Agency Director Michael Rogers and Dan Coats, the director of national intelligence, both declined to discuss their own Trump communications during a hearing last week.
White House spokesman Sean Spicer declined to say if he thought Mr Sessions should refrain from revealing his conversations with the president, saying it "depends on the scope of the questions".
He did not explicitly endorse Mr Sessions' appearance, saying in response to a question: "We're aware of it, and we'll go from there."
Mr Comey himself had a riveting appearance before the same Senate panel last week, with some key moments centred on Mr Sessions.
In a February meeting, Mr Comey said, Mr Trump told Mr Sessions and other administration officials to leave the room before asking him to drop a probe into former National Security Adviser Michael Flynn's contacts with Russia.
In addition, Mr Comey has said Mr Sessions did not respond when he complained that he did not want to be left alone with Mr Trump again. The Justice Department has denied that, saying Mr Sessions stressed to Mr Comey the need to be careful about following appropriate policies.
The former FBI director also testified that the agency had believed Mr Sessions was "inevitably going to recuse" for reasons he could not elaborate on.
"We also were aware of facts that I can't discuss in an open setting that would make his continued engagement in a Russia-related investigation problematic," Mr Comey said.
Mr Sessions' appearance before the intelligence committee is an indication of just how much the Russia investigation has shaded his tenure. White House frustrations with the Justice Department spilled into public view last week, when Mr Trump on Twitter criticised the legal strategy in defending his proposed travel ban.
Mr Spicer declined to say then that Mr Sessions enjoyed Mr Trump's confidence, though spokeswoman Sarah Huckabee Sanders said later in the week that the president had confidence "in all of his cabinet".
Though the Justice Department maintains that it has fully disclosed the extent of Mr Sessions' foreign contacts last year, he has continued to be pressed for answers about an April 2016 event at the Mayflower Hotel in Washington, where both Mr Sessions and Mr Kislyak attended a foreign policy speech by Mr Trump.
Senate Democrats have raised the possibility that Mr Sessions and Mr Kislyak could have met there, though Justice Department officials say there were no private encounters or side meetings.
Senators, including Al Franken of Minnesota and Patrick Leahy of Vermont, have asked the FBI to investigate and to determine if Mr Sessions committed perjury when he denied having had meetings with Russians.