Controversial FBI agent Peter Strzok is testifying before House lawmakers on Capitol Hill.

The focus of the hearing is the slew of Trump-bashing texts Strzok sent to his former co-worker and lover using his FBI phone while conducting investigations into Russian election meddling and Hillary Clinton's email server.

Strzok was removed from Special Counsel Robert Mueller's Russia probe earlier this year after his texts were revealed.

Peter Strzok, Lisa Page and the FBI Texting Scandal Explained

Republicans have maintained Strzok's texts with former FBI lawyer Lisa Page are evidence of anti-Trump bias within the Justice Department.

During his opening remarks, Rep. Elijah Cummings (D-Md.) accused Republican lawmakers of attempting to undermine Mueller's investigation, pointing out that the special counsel has already secured five guilty pleas and indicted 18 others.

In his opening statement, Strzok said there is no evidence of bias in his professional actions.

Strzok rejected the characterization of the Mueller probe as a “witch hunt.”

“This investigation is not politically motivated, it is not a witch hunt, it is not a hoax,” Strzok said.

“I have the utmost respect for Congress’s oversight role, but I truly believe that today’s hearing is just another victory notch in Putin’s belt and another milestone in our enemies’ campaign to tear America apart."

Chairman Bob Goodlatte (R-Va.) pressed Strzok on a text he sent to page in which he appeared to deride Trump supporters in southern Virginia. 

Strzok said he used a "quick choice of words" and that he was not looking to demean residents of any county. 

"It was an unfortunate use of words and in no way do I believe [them]," he responded.

The questioning led to several heated confrontations between lawmakers, as Democrats accused Republicans of "harassing" Strzok. 

Judge Nap: Lisa Page's Refusal to Comply With Subpoena Is 'a Head-Scratcher'

Dershowitz: Americans Deserve to Hear Strzok Explain Anti-Trump Text Messages

WATCH: Protesters Yell 'Shame' at Ivanka Trump as She Attends Roundtable in NY

Rep. Black Proposes Bill to Make Illegal Border Crossings a Felony