WASHINGTON - Standing before reporters in February, President Donald Trump said unequivocally that he knew of nobody from his campaign who was in contact with Russians during the election. Attorney General Jeff Sessions has told the Senate the same thing.

Court documents unsealed this week cast doubt on both statements and raised the possibility that Sessions could be called back to Congress for further questioning.

The special counsel, Robert Mueller, unsealed his first charges Monday in a wide-ranging investigation into Russian attempts to disrupt the presidential election and whether anyone close to Trump was involved. Records in that case show that George Papadopoulos, a foreign policy adviser, had frequent discussions with Russians in 2016 and trumpeted his connections in front of Trump and Sessions.

Fateful March meeting

For months, journalists have revealed evidence that associates of Trump met with Russians during the campaign and the presidential transition. But the court documents represent the first concrete evidence that Trump was personally told about ties between a campaign adviser and Russian officials.

At a March 31, 2016, meeting between Trump and his foreign policy team, Papadopoulos introduced himself and said "that he had connections that could help arrange a meeting between then-candidate Trump and President Putin," according to court records.

"He went into the pitch right away," said J.D. Gordon, a campaign adviser who attended the meeting. "He said he had a friend in London, the Russian ambassador, who could help set up a meeting with Putin."

Trump listened with interest. Sessions vehemently opposed the idea, Gordon recalled. "And he said that no one should talk about it because it might leak," he said.

Several of Trump's campaign advisers attended the March 2016 meeting, and at least two of those advisers are now in the White House: Hope Hicks, the communications director, and Stephen Miller, a senior policy adviser.

President's denial

After Trump was sworn in, he could not escape questions about Russia. At a Feb. 16, 2017, news conference, a reporter asked Trump, "Can you say whether you are aware that anyone who advised your campaign had contacts with Russia during the course of the election?"

"No," Trump said. "Nobody that I know of. Nobody."

The White House has sought to portray Papadopoulos as an insignificant figure in the campaign.

Ty Cobb, the White House lawyer dealing with matters related to Mueller's investigation, said the White House stood behind the president's comments.

"The media's willingness to inflate Papadopoulos, a young unpaid volunteer and supposed energy expert, into an important thought leader in the campaign or Russian operative is ludicrous," Cobb said. "The evidence so far suggests he attended one meeting, said something about Russia and was immediately shut down by everyone in the room. It's very important to remember that he is not a criminal now because of anything he did for the campaign - he is a criminal because he initially lied to the FBI."

A Justice Department spokesman declined to comment.

Democrats in the Senate said on Thursday that they would push to have Sessions return to the Judiciary Committee for further questioning.

"He now needs to come back before the committee, in person, under oath, to explain why he cannot seem to provide truthful, complete answers to these important and relevant questions," said Sen. Patrick J. Leahy, D-Vt., who is on the Judiciary Committee.