Corey Lewandowski at Trump Tower in New York on Dec. 7, 2016. (Jabin Botsford/The Washington Post)

President Trump has declared that he possesses "one of the great memories of all time." He seems to have surrounded himself with people who are decidedly more forgetful.

In recent weeks, unsealed court filings and congressional testimony have exposed several current and former Trump advisers who — on the subject of their own or others' dealings with Russians — did not provide an accurate account. When confronted with documents or testimony that contradicts their version of events, they have changed and blamed their shoddy memories.

Attorney General Jeff Sessions told lawmakers that he "did not have communications with the Russians," and that he was "not aware" of anyone else on the campaign who did. In fact, Sessions had talked with the Russian ambassador to the United States, and a lower-level Trump adviser had mentioned to Sessions that he had contacts who could possibly help broker a meeting between Trump and Russia's president. Sessions acknowledged as much in testimony before the House Judiciary Committee on Nov. 14.

Former campaign manager Corey Lewandowski said he did not know a onetime foreign policy adviser who traveled to Moscow during the campaign. But the adviser said he had met Lewandowski in person and later looped him in about the trip — and Lewandowski now concedes the latter point.

Carter Page, a former adviser who was once so forgettable to Lewandowski, repeatedly claimed to the House Intelligence Committee that he could not recall details of foreign trips and contacts. Longtime Trump aide Keith Schiller similarly told the committee that he couldn't recall specific conversations with Trump or some details of trips abroad, according to people familiar with his testimony.

Page, Lewandowski, Sessions and others have said they had packed schedules and interacted with countless people while working for the Trump campaign, suggesting they should not be faulted for not remembering conversations they considered inconsequential at the time. Sessions said at Tuesday's hearing that the Trump campaign was a "form of chaos every day from Day One," and that because he was still a sitting senator at the time, "sleep was in short supply."

But people's memories should be stronger when an event might involve legal liability or political scandal, said Michael R. Dougherty, the chairman of the psychology department at the University of Maryland, who researches memory. Dougherty said it is "remarkable" how consistently "things related to Russia seem to be forgotten."

"There is no clear-cut scientific way to differentiate between an authentic case of forgetting and a lie, but what we can do is ask the question: How likely is it that multiple people would fail to remember multiple instances in which Russia issues were raised?" Dougherty said. "In my mind, it's unlikely that everyone would systematically forget every instance of Russia-related discussion. Is it impossible? No. Is it unlikely? Yes."

Shifting stories and failing memories have long been a staple of those in Trump's orbit. Former national security adviser Michael Flynn, for example, claimed in January that he had not discussed U.S. sanctions with the Russian ambassador, but when confronted by The Washington Post about intercepts that showed otherwise, he said through a spokesman that he could not remember.

Donald Trump Jr. issued similarly evolving statements when confronted by the New York Times reporting on a meeting he and others had with a Russian lawyer in June 2016 at Trump Tower.

Sessions claimed at one point that he "did not have communications with the Russians," then that he had no meetings with Russians "to discuss issues of the campaign." After The Post reported otherwise, Sessions acknowledged that he met with the Russian ambassador, and that Trump's policy positions may have come up in their conversation.

The investigations by congressional committees and special counsel Robert S. Mueller III of whether the Trump campaign coordinated with Russia to influence the 2016 election have intensified the pressure on Trump advisers — bringing to light documents and testimony that call into question what they have said previously or forcing them to reveal new details.

Page testified before the House Intelligence Committee that he had met Lewandowski personally, and he had later mentioned to the campaign manager a July Moscow trip he was taking. By Page's account, Lewandowski told him, "If you'd like to go on your own, not affiliated with the campaign, you know, that's fine."

An excerpt from Carter Page’s testimony to the House Intelligence Committee. (WP/WP)

In March, Lewandowski had said emphatically on Fox News Channel: "I don't know who Carter Page is. I never had a conversation with Carter Page. I never met Carter Page. And anybody who says otherwise is just not being truthful." But Lewandowski conceded in a more recent appearance on Fox News that he had some memory of the encounter in which he told Page that he could not represent the campaign in Moscow.

"Now, my memory has been refreshed," Lewandowski said. He noted that Page had gotten in touch with him on Father's Day, the day before he was taken off the campaign, adding, "So with all due respect, there were many other things on my mind that day other than trying to understand why a volunteer was telling me he may or may not be traveling outside the country."

Lewandowski did not return a message seeking comment. In a text message exchange with a Post reporter, Page said that his direct conversation with Lewandowski lasted "less than a minute" and that there was "absolutely no reason he should remember me amidst his exceptionally busy schedule."

Page also testified that he told Sessions of his plans to travel to Moscow. That is important because in October, confronted by Sen. Al Franken (D-Minn.) on whether he believed surrogates from the Trump campaign had communications with the Russians, Sessions said: "I did not, and I'm not aware of anyone else that did, and I don't believe it happened."

An excerpt from Carter Page’s testimony to the House Intelligence Committee. (WP/WP)

Sessions said Tuesday that he did not recall his interaction with Page — although he said he did not dispute Page's account of what happened. Page noted in a text that his encounter with Sessions was brief and that his trip was "TOTALLY UNRELATED TO THE CAMPAIGN."

"Bear in mind that he was one of the most important and senior members of Congress last year, who dealt with some of the most powerful people in Washington every day," Page said. "If he HAD remembered our brief interaction, which peripherally alluded to a complete irrelevancy, I would have been completely shocked."

Sessions's October assertion already had come into question. When George Papadopoulos, a former Trump campaign foreign policy adviser, pleaded guilty to lying to FBI agents, he admitted that he told Trump and a group of other campaign officials, including Sessions, that he had contacts who could help arrange a meeting between Trump and Russian President Vladi­mir Putin.

On Nov. 14, Sessions revealed for the first time that he now recalled the March 2016 meeting with Papadopoulos at the Trump hotel, although he said he had "no clear recollection of the details of what he said."

"After reading his account, and to the best of my recollection, I believe that I wanted to make clear to him that he was not authorized to represent the campaign with the Russian government or any other foreign government, for that matter," Sessions said, adding later: "I remember the pushback. I remember that he suggested an ability to negotiate with Russians or others, and I thought he had no ability, or it would not be appropriate for him to do so."

Page was also pressed on what seemed to be discrepancies in his public statements about his contacts with Russia. Lawmakers noted that he sent an email describing "a private conversation" with a senior Russian official who spoke favorably of Trump, and wrote that he had been provided "incredible insights and outreach" by Russian lawmakers and "senior members" of Putin's administration.

That seemed to contradict Page's earlier assertion that he had exchanged brief greetings with the senior Russian official, Deputy Prime Minister Arkady Dvorkovich, after he delivered a speech at a Russian university. Page stood by his previous remarks, telling the committee that he had not meant that he met with any officials but rather that he had learned of their views about the U.S. presidential campaign from local media outlets and scholars.

Page, at other times, was more forgetful, sometimes frustrating lawmakers.

"Well, Mr. Page, what I'm trying to understand here is: You plan a trip to Budapest after meeting with the Hungarian ambassador, but you can't recall any specifics about what you discussed or why you'd be traveling there to meet with her?" Rep. Adam B. Schiff (D-Calif.) remarked as he questioned Page about a trip he took in late August 2016.

Page did have good reason not to be overly assertive. Last year, the FBI had obtained a warrant to secretly monitor his communications as part of an investigation of possible links between the Trump campaign and the Kremlin. Page said he was worried about his memory not matching a tape or email.

"The only thing I may be cautious about is my recollection not being able to match the recollection of what's been illicitly wiretapped and hacked off my computer systems based on the, you know, alleged FISA warrant," he said, referring to the Foreign Intelligence Surveillance Act. "So that's my only concern that's in the back of my head."

Ellen Nakashima, Carol D. Leonnig, Sari Horwitz and Rosalind S. Helderman contributed to this report.