Hillary Clinton's lead dwindles to 2 points in wake of FBI's email probe

Little more than a week ago, Hillary Clinton was leading Donald Trump in national polling by six points or more. Panic was setting in among Republicans that they would not only lose the White House, but maybe the House and Senate, too. Now, with only days to go before election day, the gap is just two points — and closing.

But despite Trump's improving odds, he still faces a stiff challenge in cobbling together enough states to give him a winning electoral map. Nevertheless, the momentum is not heading in Clinton's direction, a shift that was building in the polls before her trouble with emails re-emerged on Friday.

As of Tuesday's Presidential Poll Tracker update, incorporating polls in the field as late as Monday, Clinton stands at 47 per cent among decided voters, compared to 45.1 per cent for Trump. That is the narrowest gap recorded by the tracker since before the first of three presidential debates that saw Trump's poll numbers plummet.

Since Friday, the margin between the two candidates has tightened by 2.8 points, thanks to both a drop in support for Clinton and for third party candidates like Libertarian Gary Johnson and Green Party nominee Jill Stein, who now combine for just 7.9 per cent in the polls.

But can this slide for Clinton be chalked up to the news that the FBI is looking into emails that may or may not be pertinent to its previous investigation of the former secretary of state's use of a private server?

That isn't clear. While the margin has narrowed in recent days, that was part of an ongoing trend. Just over a week ago, Clinton was ahead by 6.9 points in the poll averages. By Thursday, the day before the FBI inserted itself into the presidential campaign, the gap was already down to 4.7 points.

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Trump's map still tricky

Clinton is still favoured to win the presidency because she is currently ahead in enough states to award her 317 electoral college votes, more than the 270 she needs to win. Trump trails with 221 votes.

But one major change over the last week is there are now enough swing states to theoretically put Trump in the White House. If all these swing states swung his way, he could win as many as 300 electoral college votes.

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Winning all of the swing states would be a tall order for the Republican nominee. The linchpin remains, as ever, Florida. If Trump wins all of the states in which he is leading in the polls as well as Florida — where he trails by a few tenths of a percentage point — he would need at least two of the other Democratic-leaning swing states (Colorado, Michigan, North Carolina and Wisconsin) to prevail.

Without Florida, he would need to win all four.

The odds of Trump managing this feat remain low. Based on previous cases where state polls have been off by large enough margins needed for Trump to win, his chances sit at about 18 per cent. 

National polls still too high for Trump?

How can it be that Trump, trailing in the national polls by just two points, is not in a better position at the state level? With such a tight race, why isn't he leading in more swing states?

The reason is that the national polls appear to be seeing the race differently than the state polls. 

Mitt Romney had this same problem four years ago. He came up short in 2012 by a wider margin than the national polls — but not the state polls — had predicted.

Using just the state polls to estimate national levels of support today shows Clinton still ahead by 5.8 points. That's down just 0.7 points from early last week. Her edge in the national poll average has decreased three times as much since then.

Unless the state polls (which come from a wider array of sources and sample more people than the national polls do) are missing the mark, Clinton remains a bigger favourite to win the presidency than the tightening national margin would suggest.

But there's no doubt her odds have significantly worsened in a matter of days — and at the worst possible time. 

• ANALYSIS| To paraphrase Nixon, when Clinton hides emails, it's not illegal​