Hillary Clinton remains the favourite to win the US election but her path to the presidency looks increasingly precarious.

While there is no evidence as yet that news of the FBI probe has had an impact on the polls, the fact is that Donald Trump was already gaining on her - and that trend continues.

In US presidential elections, the winner must get to 270 electoral votes, with each state allocated a number of votes based on the size of their population.

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Mrs Clinton remains favourite to win the likes of Nevada, Florida and North Carolina, but there have been recent polls showing Mr Trump leading in these key swing states.

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Were we to give each state in which there has been a recent poll showing him ahead to Mr Trump, Mrs Clinton would win by just two electoral votes. Even a relatively tiny state such as New Hampshire could swing such a race.

Admittedly this is a highly pessimistic map from Mrs Clinton's point of view - as mentioned, she remains ahead in the majority of polls in these states.

She also has a good chance of winning races in which the candidates appear roughly neck-and-neck, in the likes of Ohio and Iowa, and even the usually reliably Republican Arizona.

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But this does serve to highlight the precariousness of her lead. A relatively minor polling error in which Mr Trump has been underestimated would put him right in the race for the White House.

Clinton supporters will be watching nervously for confirmation that polls showing Trump ahead in these states are outliers - and for any movement in other swing states.

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A weakening lead in the likes of Pennsylvania, Colorado, Virginia or even New Hampshire would really set the cat among the Democrats' pigeons.

They continue to have the edge, but it's going to be an anxious final week.

:: There will be continuing coverage from the campaign trail throughout the day on Sky News. Plus every night this week, we will have a special programme - America Decides - from midnight with Jeremy Thompson.