monitoring Trump and relevant contemporary events

WASHINGTON — Standing before reporters in February, President 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 Mr. Sessions could be called back to Congress for further questioning.

The special counsel, Robert S. Mueller III, unsealed his first charges Monday in a wide-ranging investigation into Russian attempts to disrupt the presidential election and whether anyone close to Mr. 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 Mr. Trump and Mr. Sessions.

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

At a March 31, 2016, meeting between Mr. Trump and his foreign policy team, Mr. 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.”

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

Several of Mr. 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.

After Mr. Trump was sworn in, he could not escape questions about Russia. At a Feb. 16, 2017, White House news conference, a reporter asked Mr. 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,” Mr. Trump said. “Nobody that I know of. Nobody.”

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

Ty Cobb, the White House lawyer dealing with matters related to Mr. 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,” Mr. 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 F.B.I.”

A Justice Department spokesman declined to comment.

Another member of the foreign policy team, Carter Page, said on Thursday that he told Mr. Sessions in passing in June 2016 that he planned to travel to Russia for a trip “completely unrelated” to his volunteer role in the campaign. “Understandably, it was as irrelevant then as it is now,” Mr. Page said. Mr. Page traveled twice to Russia in 2016.

Democrats in the Senate said on Thursday that they would push to have Mr. 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 Senator Patrick J. Leahy, Democrat of Vermont, who is on the Judiciary Committee.

Senator Richard Blumenthal of Connecticut, another Democrat on the committee, pointed out that Mr. Sessions’s testimony was under oath and “wasn’t just some random comment he made in passing on the street.”

Mr. Sessions faced similar questions in January before the Senate Judiciary Committee, when Senator Al Franken, Democrat of Minnesota, asked him about contacts between the campaign and Russia. “I’m not aware of any of those activities,” Mr. Sessions said. He denied having any such contacts himself.

Democrats condemned those remarks as misleading when it was revealed that Mr. Sessions held meetings with the Russian ambassador during the campaign. Last month, Mr. Franken renewed his questioning.

“You don’t believe that surrogates from the Trump campaign had communications with the Russians?” he asked.

“I did not, and I’m not aware of anyone else that did,” Mr. Sessions replied. “And I don’t believe it happened.”

He did not make any reference to Mr. Papadopoulos. Mr. Sessions has said he answered honestly because he was being questioned in the context of Russian officials continuously exchanging information with campaign advisers.

Mr. Gordon said that while the March 2016 meeting technically contradicted Mr. Sessions’s testimony, he defended the attorney general.

“This is something he heard way back in March from some young man who was not authorized to speak for the campaign,” he said. “I don’t blame Senator Sessions for not remembering that.” He said that only in the political “gotcha game” could the matter be considered significant.

The court documents in the Papadopoulos case represent the most explicit evidence yet that Mr. Trump’s campaign was eager to coordinate with Russian officials to undermine his rival, Hillary Clinton. Federal investigators suspected that Russian intelligence services used intermediaries to contact Mr. Papadopoulos to gain influence with the campaign, offering “dirt” on Mrs. Clinton in the form of “thousands of emails.” Mr. Papadopoulos pleaded guilty to lying about those contacts and is cooperating with the F.B.I.

On Thursday, as news of Mr. Papadopoulos’s Russian ties continued to ripple through Washington, Mr. Franken sent a stern letter to Mr. Sessions. “This is another example in an alarming pattern in which you, the nation’s top law enforcement official, apparently failed to tell the truth, under oath,” he wrote.

The specific definition of "rigged" in this context is critical.