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Sen. Bernie Sanders, I-Vt., slammed President Donald Trump as a “pathological liar” on Friday and said he’d heard nothing in intelligence briefings that he’d been present for that suggested a top Iranian commander killed by U.S. forces had been planning imminent attacks.

“The difficulty that we have, and I don’t mean to be rude here, is that we have a president who is a pathological liar,” Sanders, a leading 2020 Democratic presidential candidate, told NBC’s “TODAY” in an exclusive interview.

“So could it be true? I guess it could be. Is it likely to be true? Probably not,” Sanders told NBC News' Savannah Guthrie.

“I think what happens in our own country and around the world is that people don’t believe much of what Trump says, and when you lie all the time, the problem is sometimes maybe you’re telling the truth and people are not going to believe you,” he added.

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Trump said Thursday that Soleimani had been plotting attacks on multiple embassies. Earlier in the day, he suggested that Soleimani had been planning to blow up the U.S. Embassy in Baghdad.

"Soleimani was actively planning new attacks, and he was looking very seriously at our embassies, and not just the embassy in Baghdad," Trump said.

Sanders, however, contended Friday that he sat in a classified intelligence briefing the day before last week's strike on Soleimani, and added, “We had all of the top-ranking intelligence people, military people, and not one word of that was mentioned.”

Democrats came away from the administration's classified briefings this week on the drone attack against Soleimani saying they hadn’t heard anything that suggested there was intelligence that showed Soleimani posed an imminent threat to the U.S.

Sanders refused to praise Trump for the decision to take out Soleimani, saying, ”When you assassinate a high-ranking official of a foreign government, you unleash anarchy.”

Sanders has emerged as a front-runner in the 2020 Democratic presidential race in polls in the early-voting states of Iowa and New Hampshire. He leads in both states in an average of recent polling conducted by RealClearPolitics — although his nearest competitor in each state isn’t far behind.

On impeachment, Sanders — who as a senator must essentially serve as a juror during Trump’s trial in the Senate — was critical of Senate Majority Leader Mitch McConnell’s decision to move forward with a trial without the support of Democrats, who have been demanding witness testimony.

“Last I heard, when you have a trial, you get witnesses,” Sanders quipped.

McConnell’s decision doesn’t prevent witnesses from being called, but it postpones a vote on the issue until later in the trial.

When asked if he felt House Speaker Nancy Pelosi, D-Calf., who has held up the trial by refraining to submit the two articles of impeachment against Trump to the Senate, should cease her delay and send them over, Sanders refused to criticize her.

“I would like Mitch McConnell to say he’s going to do the right thing,” he said.