It has accelerated a trend of Republicans moving towards Republican Donald Trump. But early data suggest Democrats in key states are unmoved, a sign that Hillary Clinton is holding together a coalition that has kept her in the lead for most of the presidential race.
What does the polling data show?
A CBS/YouGov survey of 'likely voters' across 13 battleground states showed that 1 per cent of Clinton supporters were less likely to vote for her after the announcement that the FBI is reviewing newly discovered e-mails that Director James Comey said may or may not be pertinent to the probe into her use of a private server during her tenure as Secretary of State. Among Democratic voters overall, a mere 5 per cent said they were less likely to support Clinton, with 13 per cent saying they were more likely to support her and 50 per cent saying it didn't matter.
Has it had an impact on early voting?
Initial statistics from early voting yesterday in North Carolina, Nevada and Florida don't show a drop-off for Democrats that would change the trajectory of the presidential race as a result of the FBI letter, said Michael McDonald, a University of Florida professor who runs the US Elections Project that updates early voting data daily. There was an increase of 332 Democratic votes in North Carolina yesterday compared with the same day in the 2012 election, and more registered Democrats cast ballots than Republicans yesterday in Washoe County, Nevada, a county that Republicans carried in 2012, McDonald said. There was not a falloff in early voting in Florida, he said. "I don't see any negative effect," McDonald said.
What impact has the email issue had generally?
Clinton's use of a private e-mail server as Secretary of State has dogged her campaign, earning widespread coverage with every new twist and turn and revelation. It has correlated with declining favourable ratings and the perception that she's dishonest and untrustworthy. Yet as the race has worn on, Clinton has shored up her base with a successful convention, three strong debate performances, and the often erratic behaviour of her opponent.
Will would-be supporters stick with her?
"Nothing that Comey or Clinton could do in the last nine days would make a Democrat vote for Donald Trump. I also think there's not much they can do to make them not vote," said Ken Goldstein, a professor of politics at the University of San Francisco. But 26 per cent of Republicans said the revelation made them less likely to support Clinton, giving Trump a boost with GOP voters who were already trending his way, and slightly improving his prospects. In a Washington Post-ABC national poll released today, Trump's support among likely Republican voters jumped four points to 87 per cent since last week, similar to Clinton's 88 per cent showing among Democrats.
What does that mean overall?
Goldstein said the FBI letter is "unlikely" to negate Clinton's large advantage with the Democratic-tilted electorate, and argued that polling has fluctuated too dramatically with independent voters lately to get a clear picture. For example, a 12-point lead for Clinton in the Post-ABC poll, including a slight advantage with independents, has narrowed to 1 point in one week. During that stretch, Trump pulled ahead by 19 points among independents.
What about the Electoral College?
Clinton's advantage in the electoral college was strong in polls taken before the FBI news. According to CBS News/YouGov polls released today, Clinton was leading by 8 points in Pennsylvania, 3 points in Colorado and 3 points in North Carolina. New NBC/Wall Street Journal surveys showed Clinton leading by 1 point in Florida and 6 points in North Carolina, while a Siena poll found Trump leading by 4 points in Florida.
Can Trump still win?
Trump's hopes of victory hinge on carrying the states Republicans won in 2012 as well as ones they lost - North Carolina, with Florida, Ohio, Iowa and Nevada - where polls show a close race. But even with those states, Trump would be five electoral votes short of 270. Trump would need a state like Colorado or Pennsylvania, where he has consistently trailed, to win.
Does it hamper Clinton's hopes?
The Republican coalescing before and after the FBI's jolt to the race dim hopes for Clinton to win reliably red states like Arizona, Georgia or Texas, where recent polling has shown her to be surprisingly competitive. Six days before the election, Clinton plans to campaign in Phoenix, hoping to expand the map in a state her party hasn't won in two-and-a-half decades.
Could there be positives from the FBI letter?
For both campaigns, Comey's opaque letter could help increase the odds that supporters will actually get out and vote. Since he accepted the GOP nomination in July, the rallying cry that most dependably unites Republicans behind Trump is the anti-Clinton "lock her up!" On Clinton's side, the controversy provided an opportunity to mitigate ongoing fears about complacency within her base. Campaign chairman John Podesta urged supporters to "buckle down, stay focused, and win this." He added: "You need to say you're not willing to let Trump bully or buy his way into the presidency, and you're not going to let anything stop us from making history".