FBI Director James Comey told a Senate panel on Wednesday that it would have been "catastrophic" for the bureau to not have disclosed in October, just 11 days before the presidential election, that the agency was revisiting the Hillary Clinton e-mail scandal.

The Clinton presidential campaign and many Democrats have suggested that Comey's announcements helped cement rival Donald Trump's win over Clinton.

Comey told the Senate Judiciary Committee on Wednesday that such an assertion doesn't sit well with him.

"It makes me mildly nauseous to think we had an impact on the election," he said. He later added that "I cannot consider for a second whose political futures will be affected and in what way. We have to ask ourselves what is the right thing to do and then do it."

The director told the Senate panel that to not have disclosed the re-opened investigation would have amounted to "an act of concealment." That's because he had already told lawmakers months before that the investigation was over and that no charges would be filed against Clinton. He said the renewed investigation concerning e-mail found on the laptop of a close Clinton aide's husband was opened in a "hugely significant way" that was relevant to the criminal inquiry.

"I saw two doors. One was labeled 'speak' and one was labeled 'conceal,'" Comey testified, in answering questions from Sen. Dianne Feinstein, a California Democrat, and other lawmakers on the panel.

Two days before the election, the director announced that the newly discovered e-mail did not change the bureau's position that Clinton, the Democrat running against Donald Trump for president, should not be prosecuted for using a private e-mail server while she was secretary of state.

Senate panelists wanted to know why Comey did not announce until after the election that the bureau was investigating the Trump campaign for possible collusion with the Russian government. Comey announced that investigation in March, two months after Trump took office.

He testified that he thought about coming forward last summer to publicly acknowledge that an FBI Trump campaign investigation began in July. But, he said, that would be akin to comparing apples and oranges. The Trump probe, he said, was "a separate question of do you confirm existence of a classified investigation that has just started."