Former FBI Director James Comey went after President Donald Trump and Republican members of Congress on Monday after emerging from a closed-door interview with House members, accusing the GOP of “shameful” silence in the face of the president’s attacks on the FBI.

“People who know better, including Republican members of this body, have to have the courage to stand up and speak the truth, not be cowed by mean tweets or fear of their base,” Comey told reporters. “There is a truth, and they’re not telling it. Their silence is shameful.”

He later added: “Some day they’ve got to explain to their grandchildren what they did today.”

Comey appeared on Monday before the House judiciary and oversight committees for the second time this month. Republicans, who control the House of Representatives for just a few more weeks, have been investigating the FBI’s handling of the federal investigations involving the Trump campaign and Hillary Clinton’s emails, dating back to 2016.

“So another day of Hillary Clinton’s emails and the Steele dossier,” Comey said dismissively after the interview, referring to former British spy Christopher Steele’s document alleging connections between Trump and Russia.

“This, while the president of the United States is lying about the FBI, attacking the FBI, and attacking the rule of law in this country–how does this make any sense at all?” he added.

“Republicans used to understand that the actions of a president matter, that words of a president matter, the rule of law matters, and the truth matters. Where are those Republicans today?” he said. “At some point, someone has to stand up, and in the face of fear of Fox News, fear of their base, fear of mean tweets, stand up for the values of this country and not slink away into retirement.”

Comey also dismissed Republican criticisms of how the FBI handled its interview of Michael Flynn, Trump’s former national security adviser who pleaded guilty to lying to the agency and has been cooperating with federal prosecutors.

“Oh come on,” Comey said with a laugh. “Think of what’s happening to the Republican party. They’re up here attacking the FBI’s investigation of a guy who pled guilty to lying to the FBI. ‘He should have been warned you shouldn’t lie. He should have been told you can have a lawyer.’ Think of the state of affairs we’ve ended up in. That’s nonsense.”

After Comey’s testimony, Rep. Mark Meadows (R-NC), a top Republican on the oversight committee and a staunch Trump ally, said Comey “didn’t follow protocol” with the agency’s interview of Flynn, and “treated different people by different rules,” citing the fact that Flynn was not warned in advance that it was a crime to lie to federal agents.

Flynn’s attorneys have claimed that the former national security adviser was coerced into lying to the FBI about his conversations with then-Russian ambassador Sergei Kislyak, but special counsel Robert Mueller’s prosecutors fired back, writing: “Nothing about the way the interview was arranged or conducted caused the defendant to make false statements to the FBI.”

Comey had asked for his testimony to be in public, but Republicans sent Comey and his attorneys a subpoena earlier this month to compel him to testify in private. The two sides later agreed that Comey would speak with lawmakers behind closed doors, but that a transcript of the testimony would be released the following day.

Democrats have accused Republicans of using their perches on powerful congressional committees to protect Trump and to attack the credibility of his adversaries.