"It was a hard choice, I still believe in retrospect the right choice", Comey told senators at a judiciary committee hearing on oversight of his agency.
Comey told the Senate panel that the thought that he might have influenced the election "makes me mildly nauseous".
Comey defended his decision to notify Congress by saying he was faced with two options - either saying something or holding back.
Clinton is now working with former aides and donors to build the organisation - Onward Together, an homage to her campaign slogan - that will look to fund and invest in groups that have impressed her since her 2016 presidential election defeat, officials with knowledge of the plans told CNN on Thursday.
"If the election had been on October 27, I would be your president", Clinton said in a TV interview Tuesday.
"Syria is another one of those wicked problems which everybody is, you know, desperately trying to figure out how to stop a civil war, how to prevent Iran from increasing its influence, how to prevent Russian Federation from having a real foot hold in the Middle East, which is something that they are desperately seeking", she said.
Because what triggered Comey's disclosure was the FBI's sudden discovery of "hundreds of thousands" of Clinton e-mails - some with classified material - on serial sexter Anthony Weiner's computer.
"Because of the 2016 election, they know it worked", Comey also said at the Wednesday hearing, according to the Independent. Chuck Grassley, R-Iowa., asked Comey if the FBI was investigating whether members of the Obama administration leaked information about the Trump team to the media.
"My understanding is they have attempted it in other countries", Comey said in response to another question from Graham. "We didn't say a word about it months into it, and the only thing we have confirmed so far about this is same thing with the Clinton investigation, that we are investigating".
James Comey was answering a question on whether Russian Federation represented a threat to the USA "democratic process", when he branded Russian Federation the "greatest threat of any nation on Earth, given their intent and capability." .
"Not for a moment", he said he replied, "because down that path lies the death of the Federal Bureau of Investigation".
Comey said he didn't publicly disclose the FBI investigation into the Clinton emails until it was closed last summer.
FBI Director James Comey walks on Capitol Hill in Washington, Thursday, May 4, 2017.
"I sat there that morning and could not see a door labeled, 'No action here, '" Comey said. Though officials found many new emails, officials again found insufficient evidence that anyone had meant to break the law, Comey said.
He also declined to say who was under investigation in the Russia-Trump associate investigation. Political group will be called "Together forward" (Onward Together), which reminds the slogan of the campaign, Clinton ("Together stronger", Stronger Together).
Kremlin spokesman Dmitry Peskov said there was no need for a separate comment on Comey's remark, following what Spicer had said. She said her effort also was damaged by the WikiLeaks release of her campaign chairman John Podesta's emails, allegedly stolen by Russian hackers.