Former FBI director James Comey, speaking for the first time since his abrupt firing last month by President Trump, told a Senate panel Thursday Trump “defamed me and the FBI’’ when the president dismissed him last month.

"Those were lies, plain and simple, and I am so sorry the FBI workforce had to hear them, and the American people were told them," Comey said of Trump's statements about his firing.

Comey said he could not say whether Trump engaged in obstruction of justice when the president asked him to drop the FBI's investigation of Michael Flynn, Trump's former , national security adviser. However, Flynn was in "legal jeopardy" at the time that Trump made his appeal, Comey said.

Richard Burr, R-N.C. said it's important for Americans to hear Comey's story.

"The American people need to hear your side of the story, just as they need to hear the President’s description of events," Burr said in his opening statement. "These interactions also highlight the importance of this Committee’s ongoing (Russia) investigation. Our experienced staff is interviewing all the relevant parties and some of the most sensitive intelligence in our country’s possession. We will establish the facts — separate from rampant speculation — and lay them out for the American people to make their own judgement. Only then will we, as a nation, be able to move forward and put this episode to rest."

Virginia Sen. Mark Warner, the top Democrat on the Senate panel, described Comey’s prepared testimony as “disturbing.’’ He cited Trump’s request for “loyalty’’ at a Jan. 27 dinner and a separate effort to press the director to drop the FBI’s investigation into former national security adviser Michael Flynn at a Feb. 14 White House meeting as particularly troubling.

“"I do want to emphasize what is happening here,’" Warner said in a statement Thursday. "The president of the United States is asking the FBI director to drop an ongoing investigation into the president’s former National Security Advisor."

"In further violation of clear guidelines put in place after Watergate to prevent any whiff of political interference by the White House into FBI investigations, the president then called the FBI director on two separate occasions ( March 30 and April 11) and asked him to ‘lift the cloud’ of the Russia investigation," Warner said.

Comey's testimony has become a huge political spectacle, attracting crowds at the Capitol and at bars showing the event live.

Spectators, most of them young congressional staffers, began lining up outside the Senate Intelligence Committee's hearing room hours before the doors opened. Seven folding tables reserved spots for more than 100 reporters were positioned just behind the witness table.

Among the group of Comey supporters seated just behind the witness table was former Manhattan U.S. Attorney Preet Bharara. Earlier this year, Bharara was famously fired by Trump during an abrupt purge of top Justice Department prosecutors.

The Intelligence Committee posted Comey's explosive seven-page statement on its website Wednesday afternoon, ending speculation about what Comey would say to the panel on Thursday. But senators were still anxious to hear directly from Comey and to question him about details of his conversations with Trump and why he kept those details quiet for months.

Trump abruptly fired Comey last month in the midst of the FBI's investigation into Russia's interference in the 2016 presidential election and possible collusion between the Trump campaign and Russian officials.

Comey's written testimony describes several different contacts he had with Trump, including a Jan. 27 dinner where he said the president told him, "I need loyalty. I expect loyalty."

"I didn’t move, speak or change my facial expression in any way during the awkward silence that followed," Comey said of the exchange.

At a Feb. 14 meeting at the White House, Comey said Trump strongly defended Flynn, arguing that his former national security adviser “hadn’t done anything wrong’’ in his prior contact with Russian ambassador Sergey Kislyak. Flynn had been fired the day before for lying to administration officials, including Vice President Pence, about his communications with Kislyak.

“I hope you can see your way clear to letting this go," Comey quoted the president as saying. "He is a good guy. I hope you can let this go."

Trump's defenders pointed to Comey's statement to underscore the president's assertion that the former director had assured him that he wasn't under investigation as part of the Russia probe.

Comey's statement says that he told Trump at their first meeting on Jan. 6 in New York City that the FBI wasn't investigating him personally.

"Prior to the January 6 meeting, I discussed with the FBI’s leadership team whether I should be prepared to assure President-Elect Trump that we were not investigating him personally. That was true; we did not have an open counter-intelligence case on him," Comey said in his statement. "We agreed I should do so if circumstances warranted. During our one-on-one meeting at Trump Tower, based on President Elect Trump’s reaction to the briefing and without him directly asking the question, I offered that assurance."

Who are the key people to watch?

The chairman of the committee, Sen. Richard Burr, R-N.C., and the top Democrat, Sen. Mark Warner, D-Va., have been careful to proceed in a very collegial bipartisan manner.

It's worth noting that the senators on the committee represent a broad ideological spectrum: John Cornyn, R-Texas, is the second-ranking Republican in the U.S. Senate and was considered a top candidate to replace Comey at the FBI until he withdrew his name from consideration; Sen. Kamala Harris, D-Calif., a freshman senator, has been a vocal part of the Democratic "resistance" to Trump's presidency.

What about Sen. John McCain?

Sen. John McCain will also get a seat on the dais for the hearing.

McCain, R-Ariz., is chairman of the influential Senate Armed Services Committee, which also makes him an ex-officio member of the Intelligence Committee.