FBI Director James B. Comey vigorously defended his actions ahead of the 2016 presidential election when it came to criminal investigations about candidates, as senators from both political parties warned him at a hearing Wednesday that the agency’s reputation was on the line.

Comey testified at the Senate Judiciary Committee the day after Hillary Clinton blamed him in part for her election loss, since he told Congress just 11 days before the election that the agency was reopening a criminal probe into her use of personal email to improperly send classified information when she was secretary of State.

“This is terrible. It makes me mildly nauseous to think that we might have had some impact on the election,” Comey said. “But honestly, it wouldn’t change the decision.”

Under questioning from California Democratic Sen. Dianne Feinstein, Comey described his choice last October as one between the “really bad” option of telling Congress and possibly affecting the election and a “catastrophic” option of concealing that information from lawmakers.

Although the Clinton investigation was closed, Comey said, investigators decided they needed a search warrant for thousands of emails the agency found on a computer owned by Anthony Weiner, a former New York congressman who is married to Clinton’s top aide, Huma Abedin.

Comey said after a discussion with top aides he decided the FBI could not conceal that search — which could’ve revealed “golden” emails showing possible evidence of a Clinton criminal motive — even if it meant that would help Donald Trump win the election.

“As between really bad and catastrophic, I said to my team, we’ve got to walk into the world of really bad,” Comey testified. The emails on Weiner’s computer contained classified materials but no evidence of intent to commit a crime, he added.

Feinstein called that decision to inform Congress in a letter and not in a classified way “an enormous gamble” that there was something on Weiner’s computer that would invalidate Clinton’s candidacy. “And there wasn’t,” Feinstein said.

Sen. Patrick J. Leahy, D-Vt., said many Americans are “confused and disappointed” that Comey aired information about the Clinton investigation before the election but not about the ongoing probe into Russia’s effort to affect the 2016 presidential contest. Sen. Chris Coons, D-Del., asked Comey questions about why he distinguished between the two.

“I thought it was very important to call out what the Russians were trying to do with our election and I offered in August myself to be a voice for that in a public piece,” Comey told Coons, adding that the Obama administration didn’t take advantage of that information but did reveal it in October.

“That’s a separate question from: Do you confirm the existence of a classified investigation that has just started to try to figure out are any connections between that Russian activity and U.S. persons,” Comey said. “The Hillary Clinton investigation we didn’t confirm it existed until three months after it started, and it started publicly.”

It was not clear at the time what the FBI would find in the Trump investigation, Comey said. The FBI has confirmed the existence of the Trump-Russia investigation but has not yet announced any result.

Concerns were bipartisan, however. Judiciary Chairman Charles E. Grassley told Comey that “a cloud of doubt hangs over the FBI’s objectivity” because of how the Clinton probe was handled. The Iowa Republican also raised questions about the investigation looking at connections between Russia and the Trump campaign, and how much the agency has relied on a controversial intelligence dossier that includes explosive allegations.

Comey often said he could not publicly comment about the Trump campaign. He testified for several hours in the wide-ranging oversight hearing, his first appearance at such a hearing since 2015.

Sen. Richard Blumenthal, D-Conn., asked Comey if he had any regrets about any decisions he made regarding disclosure of those two investigations.

“The honest answer is no,” the FBI director said.

Sen. Sheldon Whitehouse told Comey he had a different take on the Clinton email investigation. “I don’t doubt your honesty for a minute, but I do think that there were very significant mistakes made through this process,” the Rhode Island Democrat said.