WASHINGTON — For Attorney General Jeff Sessions, questions about the Trump campaign and Russia have become a headache that won’t go away.

Three times he has appeared before his former colleagues in the Senate and answered questions about what he knew about contacts with Russians during the campaign.

Three times Sessions has stumbled, issuing denials that later proved to be incomplete or wrong.

On Tuesday, the nation’s highest lawman will face another grilling on Capitol Hill, this time prompted by claims in court documents and congressional testimony that he was told of at least two aides’ meetings with Russian officials — despite his claim last month that he was unaware of any such contacts.

“The facts appear to contradict your sworn testimony on several occasions,” all 17 Democrats on the House Judiciary Committee wrote to Sessions last week in advance of his appearance there.

The latest disclosures still fall short of evidence that anyone in the Trump campaign was directly involved with Russia’s attempts to influence the election through computer hacking and social media — much less that Sessions knew about it.

But Sessions’ serial inconsistencies have given Democrats an opening to hammer his credibility.

They also helped fuel congressional investigations into the Russian meddling and the possible involvement of the Trump campaign, the focus of the criminal investigation led by special counsel Robert Mueller.

It’s a potential crime to lie to Congress, though prosecutions for perjury are extremely rare. But the controversy already has damaged trust in Sessions, who also endured an extraordinary public flogging by President Donald Trump over the summer for recusing himself from the Russia probe.

The shifting accounts “will dog him throughout his tenure as attorney general,” said Laurie Levenson, a former federal prosecutor now a professor at Loyola Law School in Los Angeles. Sessions has been “neutered” by questions about his probity, she said.

“If the person on the highest level sworn to uphold the law is the one you cannot trust, that’s a big problem for the entire Justice Department,” she said.

Meanwhile Monday, the Justice Department said Sessions is leaving open the possibility that a special counsel could be appointed to look into Clinton Foundation dealings and an Obama-era uranium deal. Such a move likely would to lead to Democratic complaints about an undue political influence on the department’s decision-making.

In a letter to the House Judiciary Committee, the Justice Department said Sessions had directed senior federal prosecutors to “evaluate certain issues” recently raised by Republican lawmakers.

A former U.S. prosecutor and four-term U.S. senator from Alabama, Sessions endorsed Trump in early 2016, boosting the novice candidate when most GOP leaders were shunning him. Sessions became head of the campaign’s foreign policy team, and he soon echoed Trump’s friendlier policies toward Russian President Vladimir Putin.

That March, Trump named several foreign policy advisers to work under Sessions, including energy consultants Carter Page and George Papadopoulos. Neither was known in foreign policy circles, and both soon met with Russian intermediaries — and say they told Sessions about it.

According to court papers, Papadopoulos, who lived in London, met a professor there who said the Russians had “dirt” on Hillary Clinton, including “thousands of emails.” This was several months before the first hacked emails were released to the public. He also met a woman who he thought was Putin’s niece.

In follow-up emails, Papadopoulos was urged to arrange a meeting between Trump or his top aides and senior Kremlin officials.

On March 31, 2016, Papadopoulous sat at a long conference table in New York with Trump on one end and Sessions at the other. At one point, the 30-year-old aide bragged about his Russian connections and his efforts to set up a meeting with Putin.

“He was shut down pretty quickly by Senator Sessions, and no such meeting (with the Kremlin) ever happened,” said J.D. Gordon, a former Pentagon spokesman also at the meeting. Gordon said Sessions said he would “prefer that nobody speak about this again.”

Papadopoulos has pleaded guilty to lying to the FBI about his Russian contacts.

Page also says he informed Sessions about his contacts in Russia.

Page told the House Intelligence Committee that in July 2016 he confided in Sessions, after a dinner at the Capitol Hill Club, about his plans to deliver a speech in Moscow. While there, Page also told the committee, he had a “private discussion” with one of Russia’s deputy prime ministers and met several Russian lawmakers.

Page told the panel that he “just mentioned it (to Sessions) in passing,” according to a transcript. “He had no reaction whatsoever.” In an email, Page said he wasn’t surprised that Sessions didn’t recall the encounter and said the trip was “totally unrelated” to the campaign.

Associated Press contributed.

joseph.tanfani@latimes.com