Former FBI Director James Comey plans to say in public testimony before a Senate committee President Trump pressured him to end the FBI's investigation into ties between Trump's campaign associates and Russia, according to a report.

CNN reported Wednesday Comey's testimony before the Senate Intelligence Committee could come as early as next week. However, no official date has been set.

Trump fired the former FBI director earlier this month, and the Justice Department appointed a special counsel, former FBI Director Robert Mueller, to lead the investigation into Russia's meddling in the 2016 election.

Some members of Congress were concerned Mueller's appointment would affect Comey's ability to testify publicly.

But CNN said Comey and Mueller met privately and discussed the parameters for Comey's testimony to safeguard against "legal entanglements."

The former FBI director's testimony will come as Democrats are alleging Trump may have attempted to obstruct the probe into whether associates on his campaign colluded with Russian officials.

Democrats made their allegations after reports indicated Comey recorded his interactions with the president in memos — including one conversation in which the president allegedly asked the former FBI director to end his investigation into Michael Flynn, Trump's former national security adviser who was fired in February.

Those accounts are likely to be part of Comey's public testimony, a source told CNN.

"The bottom line is he's going to testify. He's happy to testify, and he's happy to cooperate," the source said.

When asked about Comey's upcoming testimony, White House press secretary Sean Spicer referred questions on the investigation to Marc Kasowitz, the president's outside counsel.

"We are focused on the president's agenda and going forward," Spicer said.

In addition to the FBI's investigation into Russia's influence on the 2016 election, a number of House and Senate committees are also looking into ties between Trump's campaign associates and Russia.

Several congressional panels have asked the FBI for copies of memos Comey wrote memorializing his interactions with the president.

No evidence of collusion between Trump campaign aides and the Russian government has been presented.