(ABC NEWS) -- Former FBI Director James Comey laced into President Trump and the White House during his much-anticipated congressional testimony today, accusing the administration of working to "defame" him and the FBI, and telling "lies" to the American people.

“Although the law requires no reason at all to fire an FBI director, the administration then chose to defame me and, more importantly, the FBI by saying that the organization was in disarray, that it was poorly led, that the workforce had lost confidence in its leader,” Comey said in his opening remarks to the Senate Select Committee on Intelligence in a hearing room on Capitol Hill.

"Those were lies plain and simple. And I am so sorry that the FBI work force had to hear them and I am so sorry that the American people were told them.”

Among other things, Comey also said during the course of his testimony:

  • The Trump administration tried to smear his reputation;
  • The president had said Comey was "doing a great job" before his firing;
  • He had a “very, very awkward" relationship with Trump;
  • He believes he was “fired because of the Russia investigation”;
  • And Trump never explicitly told him to drop the Michael Flynn investigation.

Comey also described a series of uncomfortable interactions with Trump, in which he says the president requested his loyalty and pressed him to drop the investigation into former national security adviser Michael Flynn, who was fired after the White House said he misrepresented the nature of his contact with the Russian ambassador to the United States. Comey also said he told the president that he was not the subject of an FBI investigation.

Some of the allegations have been directly contradicted by the White House in the past. On May 12, press secretary Sean Spicer rejected the notion that Trump ever asked Comey to pledge loyalty, and on May 18 Trump himself said he never urged Comey to back off the investigation into Flynn.

“The president disputes that he ever asked for Jim Comey’s loyalty and he disputes that he ever asked Comey to let the Flynn investigation go in any way,” a source familiar with the president’s thinking told ABC News today.