Presumptive Democratic presidential nominee Hillary Clinton struggled over the weekend to put behind her the stain of FBI Director James B. Comey’s finding that she had been “extremely careless” but not criminally culpable in her handling of highly classified material during her four years as secretary of state.

“I am certainly relieved and glad that the investigation has concluded,” Clinton told CNN on Sunday, regarding her practice of using a private server to handle all of her official email correspondence, which exposed hundreds of classified documents to potential hacking and violated State Department and federal protocol. “But I also know how important it is to make sure everybody understands that I would certainly not do that again.”

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Yet the FBI findings of rampant mishandling of sensitive emails stunned Republicans and Democrats alike and further undermined public confidence in her honesty and integrity. A new Washington Post/ABC News poll released on Monday found that a solid majority of Americans – 56 percent – disapprove of Comey’s recommendation to the Justice Department last week against charging Clinton with a federal crime. Only 35 percent of those interviewed said they approved of Comey’s recommendation.

Moreover, 57 percent of Americans said the revelations make them worry about how Clinton might handle her responsibilities if she is elected president. That represents a huge setback for a presidential candidate who has touted her government experience and steady hand in shaping foreign policy and who has repeatedly attacked billionaire Donald Trump, the presumptive GOP presidential nominee, for lacking the “temperament” and knowledge to be the next commander in chief.

Some 57 percent of registered voters interviewed July 6 through 7 indicated they were “very worried” or “somewhat worried” about how Clinton might handle her responsibilities if she is elected president in November. Fourteen percent said they don’t think the FBI findings and her abilities as president are connected, and the rest had no opinion, according to the poll.

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Precisely how the controversy over Clinton’s mishandling of her emails will impact the campaign going forward is essentially guesswork. Clinton has campaigned for the nomination for the past year with the FBI investigation and Republican-inspired congressional investigations hanging over her, and still holds a modest five-point lead over Trump in the national polls.

Not surprisingly, many voters view the controversy through a partisan prism, with nine in 10 Republicans polled saying that they disagree with Comey’s recommendation while only a third of Democrats indicating they disagreed with the recommendation.

More significantly, six in 10 independents indicated that they thought the FBI should seek criminal charges against the former secretary of state and first lady. Clinton must woo a significant portion of independent voters in key battle ground states in order to defeat Trump. And more than 40 percent of liberals and 36 percent of non-white Americans said the controversy raises their concerns about how Clinton might handle her duties as president.

Throughout the Democratic primary campaign, Sen. Bernie Sanders of Vermont questioned Clinton’s “judgment” as both a senator and secretary of state on key foreign policy and trade issues. Sanders is expected to formally endorse Clinton for president on Tuesday, during a joint campaign appearance in New Hampshire. His support may be critically important to Clinton in trying to assuage renewed concerns among liberals about her credibility and judgement.

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This will be especially true as Republicans try to keep the issue front and center with campaign ads highlighting Comey’s criticism of Clinton’s mishandling of government email and House Republicans’ efforts to get the FBI to investigate whether Clinton lied about her emails to a special House committee that investigated the 2012 terrorist attack on a U.S. diplomatic outpost in Benghazi, Libya.

Perhaps the only piece of good news for Clinton in the new survey is that registered voters critical of Comey’s decision not to seek criminal charges are divided on whether the outcome of the investigation makes them less likely to vote for Clinton in November. Some 47 percent said it will make no difference to them on how they will vote, while 45 percent said they are now less likely to support her.

Jim Manley, a Democratic strategist and former Senate leadership spokesman, said on Monday that voters have been wrestling with Clinton’s email problems for months and pretty much made up their minds whether to support her before Comey’s July 5 announcement.

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“As far as I’m concerned, the cake is baked here,” Manley said in an interview. “Most folks made up their minds a long time ago whether they thought there was something suspicious here or not. It will continue to be an issue on the campaign trail, but I don’t see it moving very many, if any, votes.

“Republicans are busy crafting the 30-second attack ads, but I don’t think it’s going to move the dial,” he added. “Most people made up their minds about Hillary Clinton a long time ago.”