FBI Director James B. Comey on Wednesday stood by his controversial decision to announce last October that the bureau had reopened its investigation into Democratic presidential candidate Hillary Clinton Hillary Diane Rodham ClintonBiden courts veterans amid fallout from Trump military controversies Biden looks to shore up Latino support in Florida MLB owner: It's 'very necessary' to vote for Trump MORE’s private email server.

But, he told a Senate panel, "It makes me mildly nauseous to think we had an impact on the election."

In a long and passionate defense during which he repeatedly rapped a hand on the table, Comey told the Senate Judiciary Committee that it would have been “catastrophic” to keep silent the discovery of new emails considered pertinent to the then-closed probe.

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Having already told Congress that the bureau had completed the probe without recommending charges, to restart it in “a hugely significant way” and not inform lawmakers “would require an act of concealment,” he said.

“I sat there that morning and I could not see a door labeled 'no action here,'” he said in response to questions from ranking member Dianne Feinstein Dianne Emiel FeinsteinDemocrats back away from quick reversal of Trump tax cuts Congress must save the Postal Service from collapse — our economy depends on it Emboldened Democrats haggle over 2021 agenda MORE (D-Calif.). “I saw two doors. One was labeled 'speak' and one was labeled 'conceal.'”

On Oct. 28, 11 days before Election Day, Comey sent a letter to Congress informing lawmakers that investigators had uncovered emails that appeared to be pertinent to the bureau’s probe, considered completed at the time, of Clinton’s private email server.

Although the bureau eventually announced that its review of the new emails did not change their original conclusion that no charges were appropriate against the then-Democratic presidential nominee, the announcement roiled the final days of the election.

Clinton’s team has blamed her shocking loss on the announcement.

Comey's testimony on Wednesday was perhaps his most detailed accounting yet of his thinking leading up to the high-stakes decision.

Feinstein and other Democrats on Wednesday expressed bafflement that Comey should disclose so much about the Clinton probe but not the investigation, confirmed only this month, into Trump campaign ties with Russia.

Comey argued Wednesday that the difference was that the Clinton probe, on Oct. 28, had been closed — and further, that he had already testified before Congress that "there's nothing there."

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