Both national polls and surveys in swing states show Clinton has seen a slide with voters younger than 35, particularly when Libertarian candidate Gary Johnson and Green Party candidate Jill Stein are factored in.

A national Quinnipiac poll showed Clinton capturing 31% of the vote among voters 18-to-34 years of age and a slim 5-point lead over Trump. In August Clinton had 48% of that vote and a 24-point lead over Trump.

A Fox News poll of the national electorate showed Clinton winning 37% of the youth vote and leading Donald Trump by 9 points. In August, the poll showed her support at 39% and leading Trump by 8 points.

In Ohio, a CBS/YouGov poll showed Clinton doing better with voters under 30, winning 51% of them and holding 32-point lead on Trump. But that number was down from August when Clinton won 57% of that vote and a held a 38-point lead.

A Detroit Free Press poll in Michigan showed a big dip among voters under 35. In the new poll she has 31% of that vote and a 7-point lead over Trump. In August she had 44% of that vote and a 24-point lead.

The lower numbers are a big problem for Clinton because Democrats need a lot of votes from the younger part of the electorate to offset losses they normally get with older voters.