WASHINGTON (NBC News) — Embattled Attorney General Jeff Sessions on Tuesday blasted allegations that he or anybody in the Trump campaign colluded with the Russians as an "appalling and detestable lie." 

"Let me state this clearly: I have never met with or had any conversations with Russians or any foreign officials concerning any ... interference with any campaign or election," Sessions testified before the Senate Intelligence Committee. 

"Further, I have no knowledge of any such conversations by anyone connected to the Trump campaign. I was your colleague in this body for 20 years, and the suggestion that I participated in any collusion or that I was aware of any collusion with the Russian government to hurt this country, which I have served with honor over 35 years, or to undermine the integrity of our democratic process is an appalling and detestable lie."

"Please colleagues, hear me on this," Sessions continued. "I recused myself from any investigation into" alleged Russian meddling in the presidential campaign. "I did not recuse myself from defending my honor against scurrilous and false allegations."

It was the dramatic start to Sessions' much-anticipated sworn appearance before the committee. And his testimony came on the heels of fired FBI Director James Comey’s turn last week before the same panel — a two hour and 40 minute evisceration of Trump during which Comey called the president a liar and said he was fired because of “the Russian investigation.” 

Early on, the questioning of Sessions grew heated as he declined to answer several questions about private conversations with Trump. 

Sessions stopped short of invoking executive privilege — he said only the president can do that — but explained that he was following the "longstanding" policy of the Justice Department by drawing a veil on his conversations with Trump. And he objected when Senator Ron Wyden, an Oregon Democrat, suggested he was stonewalling. 

"I am not stonewalling," an emotional Sessions insisted. 

Then, when Wyden asked Sessions why he didn't recuse himself from the decision to fire Comey, the AG answered, "It did not violate my recusal." 

"That answer, in my view, does not pass the smell test," Wyden shot back.

Sessions arrived at the Capitol with Washington roiling over reports that Trump was considering removing Robert Mueller, the special counsel leading the Russian probe. 

It was the first time Sessions testified before Congress since he took office in February. And while Sessions — under pressure from Democrats — agreed to do so in public, no time was set aside for a closed hearing where the AG would be free to discuss classified matters. 

Asked whether Trump has confidence in Mueller, Sessions answered, "I have confidence in Mr. Mueller, but I'm not going to discuss any hypotheticals."

Sessions arrived knowing he would likely be questioned about his contacts with Russian Ambassador Sergey Kislyak — including an alleged third private meeting with the diplomat at the Mayflower Hotel in April 2016. NBC News has reported that the FBI is also looking into the alleged Mayflower meeting. 

The AG forcefully denied meeting with Kislyak at the hotel. "I came there not knowing he would be there," he said. 

Sessions also said nobody in the Trump administration has ordered him to do anything "improper" or "illegal."

The AG also faced other key questions like whether he still stands by his original explanation that Comey was fired for his handling of the Hillary Clinton email investigation during the campaign last year. Trump told NBC Nightly News anchor Lester Holt that Comey’s ouster was related to the Russia probe.

The White House spun Comey’s admission before the committee that Trump was not personally under investigation into a “Comey vindicates Trump” talking point. And a Republican rapid-response messaging team is poised and ready to spring into action the minute Sessions gets sworn in and starts answering questions. 

How did Trump feel about Sessions appearing before the panel? Sessions did not say. 

But Trump was reportedly not happy when Sessions announced in March that he was recusing himself from the federal probe of Russian meddling in the presidential election.

Insisting again that he had no improper contacts with the Russian, Sessions said at the time he was stepping aside from this mater because of his involvement in the Trump campaign. “I should not be involved in investigating a campaign I had a role in,” he said. 

But Sessions’ decision to recuse himself came after he first caught flak for not disclosing during his confirmation hearing that he met with Kislyak twice during the campaign. 

Sessions told NBC News a similar story on the morning of March 2. “I have not met any Russians at any time to discuss any political campaign,” he said. “And those remarks are unbelievable to me and are false.” 

A couple hours later, Sessions was singing a somewhat different tune. 

“In retrospect, I should have slowed down and said, ‘But I did meet with one Russian official a couple times, that would be the ambassador,” he told reporters. 

Sessions is also likely to tell the Senators that he has been steering clear of the ongoing Russia probe, a claim that was buttressed earlier Tuesday by Deputy Attorney General Rod Rosenstein. 

“I know what we’re investigating,” Rosenstein said Tuesday. “He does not.”