Hillary Clinton has tried to move past the issue of using private e-mail while secretary of state, and rival Bernie Sanders gave her a big boost in that direction during Tuesday's debate. But the controversy is not going away any time soon.

"Let me say something that may not be great politics – but I think the secretary is right. That is, the American people are sick and tired of hearing about your damn e-mails," Sanders said in one of the most memorable lines of the night.

"Me, too," Clinton responded, and the two shook hands.

Clinton also again said that her use of the private e-mail server was a mistake -- but one she said was on the level.

"What I did was allowed by the State Department, but it wasn't the best choice," she said.

The breaks have recently been falling in Clinton's favor over the issue. House Majority Leader Kevin McCarthy (R-Calif.) credited the House Select Committee investigating the 2012 attacks on two U.S. outposts in Libya for bringing down Clinton’s poll numbers.

“This committee is basically an arm of the Republican National Committee,” Clinton said Tuesday night. “It is a partisan vehicle, as admitted by the House Republican majority leader, Mr. McCarthy, to drive down my poll numbers.”

Despite this, the issue has, and will, continue to dog Clinton. The FBI is investigating the security of Clinton's e-mails, and the inquiry recently grew in scope to include a second technology company. Clinton will testify later this month before the House Select Committee, which has said that her e-mail use pertains to their investigation. Concerns over the security of her system have been mounting; a technology subcontractor who worked on Clinton's e-mail setup expressed concerns that the system was vulnerable to hackers, and Clinton and the State Department have given different accounts of why they turned over e-mails.

Politically, Republicans continue to hammer Clinton on how she communicated electronically.

"I thought it was interesting that they didn’t go after her, particularly on the e-mail issue because, look, there’s an FBI investigation, she hasn’t been forthcoming," Republican presidential candidate Jeb Bush said on Fox News on Wednesday. Bush said "it's clear" that the Chinese and Russians were trying to hack into Clinton's server.

"She was secretary of state. This is information crossing that server was of national security interest for sure, and I would have taken her to task for that," Bush said. "If she wins the nomination and I win the nomination, trust me this is not going to end."

Clinton said last night that she is being transparent, has turned over thousands of pages of correspondence and pushed to testify publicly before the committee.

"I am going to be testifying. I've been asking to testify for some time and to do it in public, which was not originally agreed to," she said.

Rosalind S. Helderman contributed reporting