How has this latest email controversy changed the presidential race?

On Friday, FBI Director James Comey informed the Republican-led House Judiciary Committee that the bureau was resuming its investigation into Hillary Clinton's emails. Some 650,000 emails had been discovered on the laptop of ex-congressman Anthony Weiner, the estranged husband of top Clinton aide Huma Abedin. Weiner is currently under investigation for "sexting" an underage girl. Despite lacking evidence that any of the emails were to or from Clinton and the unlikelihood of finding such proof by polling day, Comey justified this decision on the vague grounds that they might contain information “pertinent” to her case.

Donald Trump immediately made the FBI announcement his main line of attack on Clinton. In the last weeks of the campaign, he is now touring both marginal states and ones hitherto thought to be safe Democratic ones. In contrast, Clinton is focused on shoring up her base, leaving it to congressional Democrats and others to attack Comey and accuse him of trying to influence the election outcome.

The roots of this controversy go back to 2009, when Hillary Clinton started using a private email server for all her electronic correspondence during her four-year tenure as Secretary of State. When this was revealed by the New York Times in March 2015, the article said she “may have violated federal requirements” pertaining to the security and archiving of official communications. In self-justification, Clinton claimed that having a single private server was more convenient than using separate personal and work accounts. Critics charged that the arrangement was more vulnerable to cyberattack and gave her control of what information was provided to other government bodies, notably the congressional committee investigating the 2012 Benghazi attack. Concern was fuelled further by the discovery that 33,000 supposedly private emails were deleted before the server was handed over to investigators.

A State Department report released in May 2016 asserted that, while Clinton would not have received clearance for the email arrangement if it had been sought, there was no criminal misconduct. Announcing the finding of the separate FBI investigation on 5th July, Comey criticized Clinton for “extreme carelessness” but found no “direct evidence” of unauthorized access and declared that “no reasonable prosecutor” would bring a criminal case against her.

Democratic fears that Comey may have now cost Clinton the election are probably exaggerated. Trump was narrowing the gap with her in some polls taken just before the FBI announcement. The ABC/Washington Post tracking poll, which gave Clinton a 12-point lead on 23rd October, put her ahead by just 1 percent on 30th October. However, some surveys taken since 28th October show little movement in Clinton’s support.

Trump’s impetus comes from Republican-identifying voters shifting from Libertarian candidate Gary Johnson and, more significantly, increasing support from independents. If this momentum continues, his clearest route to the White House is to win the four swing states of Iowa, Ohio, Colorado, and Florida. But failure to take all of these could be compensated by some victories in blue states like Wisconsin, Michigan, or Pennsylvania. Nate Silver’s "FiveThirtyEight" data journalism website still gives Trump only a one in four chance of winning. Early voting, much of it carried out before the FBI bombshell, favours Clinton and her get-out-the-vote ground organization is deemed much stronger.

But it remains to be seen whether this late October surprise replicates the effect of the 1980 one. Just days before the poll, Democrat Jimmy Carter raised hopes that a deal was afoot to bring the Iranian hostages home, but the initiative proved a damp squib. This crystallised voter doubts about the president’s leadership, swinging the election to Republican Ronald Reagan. The resumed FBI investigation could have a similar benefit for Trump if it solidifies the concerns of wavering and still undecided voters about Clinton’s trustworthiness.