WASHINGTON – Attorney General Jeff Sessions’s appearance Tuesday before the Senate Intelligence Committee will be a high-stakes test for a Trump official who has become a central figure in the scandal engulfing the White House over Russia and the firing of James B. Comey as FBI director but has so far kept a low profile.

Sessions, a former Republican senator from Alabama, will face tough questions from his former colleagues on a number of fronts that he has never had to publicly address in detail.

Democrats plan to ask about his contacts during the 2016 campaign with the Russian ambassador to the United States, Sergey Kislyak, which the attorney general failed to disclose fully during his confirmation hearing.

They also want him to explain his role in the firing of Comey, despite the attorney general’s recusal in March from the Russia investigation following revelations of his meetings with Kislyak.

“If, as the president said, I was fired because of the Russia investigation, why was the attorney general involved in that chain?” Comey said in testimony before the Senate Intelligence Committee last week.

Sessions also is likely to face questions about Comey’s cryptic assertion that the FBI knew of a “problematic” reason that Sessions should not oversee the investigation into Russian interference in the 2016 election.

Democratic lawmakers are skeptical that Sessions will divulge any explosive new details, especially since the attorney general could assert executive privilege regarding any questions about conversations with the president.

But they hope the hearing offers a chance to at least get Sessions on the record as either answering or dodging answers about pivotal events related to Comey and the FBI’s investigation.

“There are many unanswered and troubling questions, so the attorney general needs to be forthcoming,” said Senate Minority Leader Charles E. Schumer (D-N.Y.). “The Senate and the American people deserve to know exactly what involvement with the Russian investigation he had before his recusal, what safeguards are in place to prevent his meddling, and why he felt it was appropriate to recommend the firing of Director Comey when he was leading that investigation.”

For the embattled attorney general, the hearing will be the first time he is questioned by senators since January, when he testified during his confirmation hearing that he did not communicate with any Russian officials during the presidential campaign, when Sessions acted as an adviser to Trump.

As the White House’s political crisis over the Russia investigation has grown, the attorney general has laid low. While Sessions used to frequently answer questions from reporters after public appearances discussing his criminal justice initiatives, he stopped in late April, just before Comey was dismissed.

Sessions was originally scheduled to testify Tuesday about the Justice Department budget before the Senate and House appropriations subcommittees. On Saturday, he wrote the chairmen of both committees and said he was sending his deputy attorney general to testify in his place. He said that he would testify before the Senate Intelligence Committee instead, though it was unclear initially if the hearing would be open or closed to the public.

Late Monday morning, Sen. Richard Burr (R-N.C.) and Sen. Mark R. Warner (D-Va.) announced that the hearing would be public.

“The Attorney General has requested that this hearing be public,” Justice Department spokeswoman Sarah Isgur Flores said in a statement. “He believes it is important for the American people to hear the truth directly from him and looks forward to answering the committee’s questions tomorrow.”

No time has been scheduled for Sessions to testify separately in a closed hearing to discuss classified matters, according to Senate aides, who were not authorized to speak publicly on the matter.

Comey’s testimony last week revealed new avenues of inquiry that lawmakers are likely to pursue on Tuesday.

The former FBI director said he contacted Sessions after a meeting with Trump in the Oval Office where Sessions and Jared Kushner, Trump’s son-in-law and senior adviser, were asked to leave and Comey was alone with the president.

During that meeting, Comey said Trump asked him to stop investigating former national security adviser Michael Flynn, who had been forced to resign the day before after failing to disclose meetings with the Russian ambassador.

“I hope you can see your way clear to letting this go, to letting Flynn go,” Comey quoted Trump as saying. “He is a good guy. I hope you can let this go.”

After the meeting, Comey told Sessions that he did not want to be alone anymore with Trump and “it can’t happen that you get kicked out of the room and the president talks to me.”

Comey said Sessions responded with, essentially, a shrug.

“I have a recollection of him just kind of looking at me,” Comey testified. “I kind of got – his body language gave me the sense like, ‘What am I going to do?’ . . . He didn’t say anything.”

Ian Prior, a Justice Department spokesman, disputed that account and said that Sessions replied to Comey and said he “wanted to ensure that he and his FBI staff were following proper communications protocol with the White House.” Trump’s personal lawyer also challenged Comey’s account, saying the president never asked for the investigation to be dropped.

Sessions had a remarkable path to the attorney general post. He was an early and vocal supporter of Trump during the campaign, when most Republican lawmakers dismissed the candidate. He arrived in the job in February eager to launch ambitious efforts to combat violent crime and deport undocumented immigrants.

But officials said Sessions’s relationship with Trump has been strained since the attorney general recused himself from the Russia probe in March. The president has also criticized the Justice Department’s failed efforts to defend his travel ban in federal court. Officials said that Sessions at one point offered to resign as his relationship with the president became increasingly tense.

The Washington Post’s Ed O’Keefe and Adam Entous contributed to this report.