Polls are often conducted over multiple days, so we’re only just starting to measure the effect of the FBI’s decision to release new details of its investigation into Hillary Clinton’s private email server to lawmakers on Friday. According to the ABC/Washington Post tracking poll published on Tuesday (conducted October 27-30), the Democratic candidate has now slipped behind Donald Trump, on 45% to her Republican opponent’s 46%. The polling average calculated by RealClearPolitics, a much better indication of national sentiment, shows Clinton is now leading by just 2 percentage points, down from 5 percentage points a week ago.

Those numbers are interesting but not necessarily indicative – polling won’t neatly translate to votes. Far more important will be the turnout- especially since the two leading presidential candidates are so close in terms of unpopularity. And the candidates know it. A senior adviser to Donald Trump reportedly revealed last week that “we have three major voter suppression operations under way” intended to reduce votes for Clinton among African Americans, white liberals and young women.

Even though election day is still a week away, we already have some clues about whether turnout is lower among those groups – because more than 25m ballots have already been cast under the US early voting system. Approximately 125 million to 145 million Americans are predicted to vote in the 2016 election, so those early votes represent a significant share of the expected total.

Higher turnout than at this time in 2012

Of the 15 states that provide detailed information about those ballots, North Carolina, California and nine other states report more early voters than at the same point in the 2012 election. Ohio, Nevada, Colorado and Iowa showed a decline in early voting, and those declines were small.

Early signs of declining turnout from black voters and young voters

The early results offer mixed news for Clinton. Early votes suggest that young voters – who are much more likely than older voters to lean Democratic – might be staying at home. In 12 states, fewer Americans aged 18 to 29 have cast a ballot so far in this election compared with this point in 2012. This could be especially problematic for Clinton if this group is indicative of a broader “Bernie or bust” sentiment in which supporters of the former Democratic candidate Bernie Sanders choose to stay at home rather than voting for Clinton.

Young voters aren’t the only demographic group that appears put off. Early votes suggest that black turnout has fallen in eight states – especially in North Carolina, a state that yields 15 of the 270 electoral college votes needed to win the election and where polling suggests Clinton is in a close contest. If Trump’s strategy is indeed to suppress the black vote, that makes a lot of sense – those voters could be crucial for Clinton to secure the White House.

David Fuller's view

Just when we all thought the US Presidential Election could not possibly be lost by Hillary Clinton – ‘the least awful candidate’ in this soap opera has apparently had her comfortable lead wiped away by FBI Director James Comey (is a ‘d’ missing from that surname?).  

This has introduced more uncertainty for at least another week.  Additionally, against the background of a stalled stock market rally, traders suddenly have an excuse to chance their luck with some more short positions as the S&P 500 Index erodes initial support. 

A week can be a long time in politics, not least for this election.  Turnout could now be important, especially for Clinton if enough Bernie Sanders admirers decide not to vote.  Third party candidates could also become a factor.  Poll support for Gary Johnson and Jill Stein of the Libertarian and Green parties, respectively, is little more than 5% but that draws more from Clinton than Trump. 

Expect another week of frenzied mudslinging from the Clinton and Trump teams.  

(See also: Stocks Fall as Gold Rallies Before Fed, Vote; Swiss Franc Climbs, from Bloomberg, and Clinton vs. Trump: Who’s Leading in Battleground Polls on Nov 1? – from Heavy)