Washington (CNN) Attorney General Jeff Sessions was adamant about one thing during his hours-long testimony in front of the House judiciary committee on Tuesday : He has never lied under oath regarding what he knew and when he knew it about the interactions between the presidential campaign of Donald Trump and Russia.

"I have always told the truth, and I have answered every question as I understood them and to the best of my recollection, as I will continue to do today," Sessions angrily insisted. "I will not accept and reject accusations that I have ever lied under oath. That is a lie."

The phrase "to the best of my recollection" is doing A LOT of work in Sessions' defense.

Here's why.

In January, during his confirmation hearing in front of the Senate judiciary committee, Sessions was asked whether he was aware of any contacts between the Trump campaign and Russia. "I'm not aware of any of those activities," he said at the time.

Then, in October, again in front of the Senate judiciary committee, Sessions had this exchange with Minnesota Democratic Sen. Al Franken:

JUST WATCHED Sessions and Franken go at it again Replay More Videos ... MUST WATCH Sessions and Franken go at it again 01:57

FRANKEN: "You don't believe that surrogates from the Trump campaign had communications with the Russians?"

SESSIONS: "I did not, and I'm not aware of anyone else that did. And I don't believe it happened."

On Tuesday, Sessions said he did in fact now remember that he was part of a March 31, 2016, meeting that included both then-candidate Trump and a foreign policy adviser named George Papadopoulos.

Papadopoulos, who pleaded guilty to lying to the FBI in regard to his ties to Russia , told special counsel Robert Mueller that he boasted in that meeting that he had ties to Russia and could set up a meeting between Trump and Russian President Vladimir Putin. Attendees said that Sessions pushed back hard on that idea, insisting that it would not be smart.

George Papadopoulos, pictured second from the left in March 2016 in a National Security Meeting with President Donald Trump, far right, and Jeff Sessions, far left.

Sessions confirmed Tuesday that he not only now remembered that meeting, but also recalled, now, that he had been a voice of dissent for Papadopoulos' proposal. He said the memory came back to him when it was "revealed in the press."

Added Sessions:

"After reading Papadopoulos' 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. But I did not recall this event, which occurred 18 months before my testimony of a few weeks ago, and would gladly have reported it had I remembered it, because I pushed back against his suggestion."

What Sessions is saying that he simply didn't remember that March 31 meeting prior to it being reported in the wake of Papadopoulos' guilty plea. But, now he not only remembers the meeting but he also recalls that he spoke out against an idea for Trump to meet with Putin.

Sessions' explanation for this seeming contradiction? The Trump campaign, while brilliant, was chaotic. Here's his full answer on Tuesday:

"All of you have been in a campaign. But most of you have not participated in a presidential campaign. And none of you had a part in the Trump campaign. It was a brilliant campaign in many ways. But it was a form of chaos every day from day one. We traveled all the time, sometimes to several places in one day. Sleep was in short supply."

Which is OK! I get tired after one late night. And I am in my 40s!

But context is not Sessions' friend here.

You'll remember that during his confirmation hearings, Sessions said he had never met with any Russian officials. It was subsequently reported that Sessions had met twice with then-Russian Ambassador to the US Sergey Kislyak -- once on the sidelines of the Republican National Convention and once in his Senate office.

He explained that seeming contradiction by insisting that he simply had not recalled the RNC meeting with Kislyak, and that, in his Senate office, he had met with the ambassador in his official capacity as a senator, not as a Trump surrogate.

On Tuesday, asked about his initial failure to recollect those meeting with Kisylak -- and his initial response to the Senate judiciary committee regarding contacts between Trump campaign officials/surrogates and Russians -- Sessions said:

"My focus was on responding to the concerns that I as a surrogate was participating in a continuing series of meetings with intermediaries with the Russian government. I certainly didn't mean I'd never met a Russian in the history of my life."

It's impossible to prove that Sessions is lying or not -- whether about his meetings with Kislyak or this memory of the March 31, 2016, meeting with Papadopoulos.

But, it's also difficult to believe that Sessions simply forgot a meeting in which he was a strong voice pushing back against the idea of Trump meeting with Putin. That seems like the sort of thing -- whether you got a lot of sleep or not during the campaign -- you would remember.