WASHINGTON • The Democrats' presumptive presidential nominee Hillary Clinton may avoid criminal charges, but the searing rebuke of her "extremely careless" e-mail practices by Federal Bureau of Investigation head James Comey is likely to reverberate through the November election and, if she wins, well into her presidency.

In a statement bringing an end to the FBI investigation of Mrs Clinton's personal e-mail system while she was secretary of state, Mr Comey laid bare a litany of facts amounting to a searing admonition of her judgment, management and stewardship of state secrets.

Even as Mr Comey on Tuesday lifted a legal cloud by saying the FBI would not recommend criminal charges, he systematically obliterated many of the key defences Mrs Clinton and her advisers have offered to reassure the public in the 15 months since the discovery that she had used a private e-mail system while in office.

For instance, Mrs Clinton had insisted that she did not send or receive classified materials, but Mr Comey said the FBI found that 110 of her e-mails contained classified information.

For weeks now, Mrs Clinton has been arguing that her Republican opponent in the White House race, Mr Donald Trump, is unfit to be president and cannot be trusted in the Oval Office.

Democratic pollster Peter Hart says Mrs Clinton's struggles with trustworthiness "are not going to just all melt away", but that "it seems to me that 'Crooked Hillary' doesn't have the same sort of sting it would have had with an indictment".

She had hoped that a rally on Tuesday in Charlotte, North Carolina, with President Barack Obama - their first joint appearance of the campaign - would underscore that contrast with Mr Trump.

Instead, the remarks by Mr Comey - a Republican with a sterling reputation among leaders of both parties - delivered from a lectern at the FBI headquarters cast fresh doubt on Mrs Clinton's own fitness and trustworthiness.

"Although we did not find clear evidence that Secretary Clinton or her colleagues intended to violate laws governing the handling of classified information, there is evidence that they were extremely careless in their handling of very sensitive, highly classified information," the FBI director said.

He said he had not coordinated or reviewed his statement with any part of the government.

Although he said the FBI was referring the decision to the Justice Department, he added that "our judgment is that no reasonable prosecutor would bring such a case".

It would be highly unusual for federal prosecutors not to follow the bureau's counsel.

Republicans sought to swiftly capitalise on the situation. Mr Trump assailed Mrs Clinton for what he called her "illegal activities" and "bad judgment", and suggested the Obama administration was protecting her from prosecution.

"She was guilty, and it turned out that we're not going to press charges. It's really amazing," said Mr Trump, also in North Carolina where he held a competing rally in Raleigh. "Today is the best evidence ever that we've seen that our system is absolutely, totally rigged." He added that Mrs Clinton "is laughing at the stupidity of our system".

"We know now that these deletions include e-mails that were work-related and one big, fat, beautiful lie by Crooked Hillary. Any government employee who engaged in this kind of behaviour would be barred from handling classified information," Mr Trump argued.

Democratic pollster Peter Hart said, however, that although "it's not a clean bill of health... it's a workable situation".

He said Mrs Clinton's struggles with trustworthiness "are not going to just all melt away", but "it seems to me that 'Crooked Hillary' doesn't have the same sort of sting it would have had with an indictment".

Senior Democrats expect Mr Trump and his allies to bang the drums about the e-mail controversy for the rest of the campaign, but believe the issue will have little currency with persuadable voters short of an indictment.

"Comey cut the legs out from under the only narrative that could have hurt her," said Democratic strategist Robert Shrum. "I assume that Trump will continue to try to make hay out of this, and I think it will go about as well as the Republicans did on Whitewater or Benghazi or anything else. I just think it's fundamentally over."

WASHINGTON POST, AGENCE FRANCE-PRESSE