ATLANTA -- Jon Ossoff, hoping to become Georgia's next congressman, joined other nationally prominent Democrats in calling for a special prosecutor into alleged Russian interference in last year's presidential election.

In a tweet late Tuesday night, Ossoff, who is in a June 20 runoff in the 6th congressional district, said President Donald Trump's firing of FBI Director James Comey "raises severe questions."

11Alive also reached out to Ossoff's opponent, Republican Karen Handel, for a comment on Comey's firing, but received no reply.

Ossoff's former boss, U.S. Rep. Hank Johnson, called Trump's firing of Comey an "assault on our Republic.

"As recently as last week, Comey confirmed that the FBI has active ongoing counter terrorism and criminal investigations into Trump campaign’s connections to the Russian government's attempts to influence the outcome of this country’s most recent presidential election," Johnson said. "Taken together with the recent firings of Acting Attorney General Sally Yates and New York's U.S. Attorney Preet Bharara, today’s firing suggests an attempt to squelch investigation in an effort to cover up wrongdoing.

"The future viability of our Republic requires Congress to conduct an independent and immediate investigation led by a special prosecutor to get to the bottom of what 17 different intelligence agencies have all concluded, which is that Russia meddled in this country’s presidential election," he said.

Georgia Democratic Party chairman DuBose Porter also sent out the following tweet:

In a move that stunned the nation, President Trump fired Comey on Tuesday.

MORE: President Trump fires James Comey

In a statement, Trump says Comey's firing "will mark a new beginning" for the FBI. The White House says the search for a new FBI director will begin immediately.

Comey's firing comes days after he testified on Capitol Hill about the FBI's investigation into Russia's election meddling and possible connections between Russia and Trump's campaign.

PHOTOS: Documents surrounding James Comey's firing