Updated at 1:00 p.m. ET
Republican attacks on federal law enforcement have helped the Russian campaign to sow chaos within the United States, an embattled top FBI counterintelligence agent told Congress on Thursday.
"Russian interference in our elections constitutes a grave attack on our democracy," Peter Strzok told lawmakers in his prepared opening statement.
"Most disturbingly, it has been wildly successful — sowing discord in our nation and shaking faith in our institutions. I have the utmost respect for Congress's oversight role, but I truly believe that today's hearing is just another victory notch in [Russian President Vladimir] Putin's belt and another milestone in our enemies' campaign to tear America apart."
Strzok's statement also denied that political considerations have ever affected his official acts as an investigator.
The tone he set did not endear him with the leaders of the House Judiciary and oversight committees, which have made him and a former FBI lawyer, Lisa Page, the targets of months of attacks about political bias within the agencies.
The hearing was often raucous and seemed at times more like a TV comedy about Congress than a real committee hearing.
Judiciary Committee Chairman Bob Goodlatte, R-Va., and oversight committee Chairman Trey Gowdy, R-S.C., criticized what they called the clear bias against Trump that Strzok and Page had demonstrated, and they lectured Strzok about his refusal to answer questions based on instructions from the FBI's attorneys.
"Agent Strzok has a most unusual and largely self-serving definition of bias ... despite common sense, doesn't think he's biased," Gowdy said.
"He thinks calling someone 'destabilizing' for the country isn't biased; he thinks promising to protect the country from someone he hasn't even begun to investigate isn't biased; he thinks promising to 'stop' someone he is supposed to be fairly investigating ... isn't biased."
Democrats, led by Judiciary Committee ranking member Jerry Nadler, D-N.Y., attempted to throw a number of procedural roadblocks in the way of the majority's questions, including motions and "points of order."
Ultimately, Strzok responded to a question from Gowdy about the early portion of the Russia investigation by defending his own work and the work of the FBI. That work is safely walled off from any individual's personal political views, he said.
Strzok wound up where he began, with a condemnation of the partisan attacks on the Justice Department and FBI that he said had been corrosive of Americans' trust in federal law enforcement.
The hearing made for hours of closely watched cable news programming.
Former Attorney General Eric Holder faulted what he called Republicans' blindness to the seriousness of the threat posed by foreign interference in U.S. politics.
"House Republicans are irresponsibly more concerned with Strzok, Rosenstein and Clinton than they are with Putin/Russian actions," he wrote. "Smoke screen. Trying to delegitimize expected results of Mueller inquiry and protect people in Trump campaign and a very likely complicit President."
Strzok played important roles in both the investigation into Hillary Clinton's private email server while she was secretary of state and the investigation of Russian election interference in the 2016 presidential race now being run by Justice Department special counsel Robert Mueller.
Mueller reassigned Strzok after the Justice Department discovered highly political text messages that he sent Page during the 2016 election cycle.
In one of them, Page asked Strzok to reassure her that Trump wouldn't be president. No, Strzok replied, "we'll stop it."
Critics have charged that the messages suggest these FBI officials intended to use their power to stop Trump's campaign. Strzok, asked on Thursday, said he didn't remember sending the message, but the way he reads it now, he believes he was referring to Americans more broadly. By "we," he said Thursday, he believes he meant voters.
Strzok told lawmakers that he thought the context for the exchange was the feud in 2016 that then-candidate Trump carried on with Khizr and Ghazala Khan, parents of a soldier killed in Iraq. Strzok and Page were angry about Trump, and Strzok said on Thursday that what he remembered was being confident voters would reject Trump as part of that.
Page has told investigators that she and Strzok were having an affair, according to a Justice Department Inspector General's report about the Clinton email investigation, and that they used their work devices to conceal that from their spouses.
That meant Justice Department investigators could access all their messages, including the ones in which they criticized Trump, Vermont Sen. Bernie Sanders, former Maryland Gov. Martin O'Malley and others.
The two were faulted by the official investigation into the conduct of the Clinton email inquiry. Page has since left the bureau. Strzok remains with the FBI, albeit removed from his old investigative job.
Republicans have cited Page's and Strzok's messages as evidence of what they call bias inside federal law enforcement and that conspirators launched the Russia investigation out of partisan animus.
Strzok has met with members of the House Judiciary Committee privately, but his hearing scheduled for Thursday is open. Goodlatte said he was holding open the prospect of calling Strzok back again because he was unsatisfied with the lack of answers to some questions.
Goodlatte said he issued a subpoena to compel Page to talk to lawmakers Wednesday, but her attorney said she would not appear. Goodlatte blasted that decision on Wednesday, saying "none of her excuses hold water."
Goodlatte announced on Thursday as the Strzok hearing was taking place that he had reached an agreement with Page and that she would give an interview with lawmakers on Friday behind closed doors.
The leaders of the FBI and the Justice Department have defended the sum of the agencies' work and tried to distance themselves from the embarrassment caused by the discovery of the messages.
"We were deeply troubled by text messages exchanged between Strzok and Page that potentially indicated or created the appearance that investigative decisions were impacted by bias or improper considerations," the Justice Department's inspector general wrote in its June report.
The Strzok-Page saga has also attracted the personal attention of the president, who has frequently commented on the ongoing scandal as evidence of a "witch hunt" against him.
Trump criticized the two again ahead of the House hearing in a Twitter post from his trip to Europe.
"Ex-FBI LAYER Lisa Page today defied a House of Representatives issued Subpoena to testify before Congress! Wow, but is anybody really surprised! Together with her lover, FBI Agent Peter Strzok, she worked on the Rigged Witch Hunt, perhaps the most tainted and corrupt case EVER!"