Strzok, who headed the FBI’s counterespionage division in 2016, and was one of the top officials overseeing the criminal investigation into whether Hillary Clinton mishandled classified information while she was secretary of state, has become a lightning rod for efforts to undermine the Russia investigation due to text messages he sent to Lisa Page, a former FBI attorney with whom he was having an affair, that were deeply critical of Trump during a period in which the FBI was investigating his campaign.

Over the course of the hearing, Bob Goodlatte, the Republican chairman of the House Judiciary Committee, threatened Strzok with contempt for not revealing details related to the ongoing investigation into Russia’s election interference, Republican Congressman Louie Gohmert accused Strzok of lying under oath and disparaged Strzok’s relationship with his wife, and Republican Congressman Darrell Issa forced Strzok to read his own text messages aloud—including ones that included vulgarities.

Strzok defended himself, insisting that he was not biased and that his political beliefs never affected his work. He sought to contextualize some of the more controversial text messages he sent during the campaign, including one which said that “we” would “stop” Trump from becoming president—a text he claimed to have written “late at night” in response to Trump’s “horrible, disgusting” attacks on Khizr and Ghazala Khan, the parents of the fallen Army Captain Humayun Khan. Trump had attacked the gold-star parents, who are Muslim, after they appeared at the Democratic National Convention and denounced Trump for his call to ban Muslims from the United States.

No matter how many times Strzok insisted that his professional actions were not affected by his negative feelings toward Trump—and that agents are trained to leave their political beliefs at the door—Republicans insisted, without providing evidence, that his work had been tainted.

“I am telling you that I and the other men and women of the FBI every day take our personal beliefs and set those aside in vigorous pursuit of the truth, wherever it lies,” Strzok told Representative Ted Poe. “And I don't believe you,” Poe replied.

Even as Republicans demanded complete transparency from Strzok—who supervised the Russia probe under former FBI Director James Comey until Special Counsel Robert Mueller was appointed last May, after Trump fired Comey—they declined to release a transcript of Strzok’s first appearance before the committee. Democrats described that 11-hour closed-door grilling as “an attempt to obstruct” Mueller’s work and act as Trump’s “defense counsel,” and Democratic Representative David Cicilline threatened to release the transcript unilaterally unless Republicans could name a specific House rule that prevented him from doing so.