Like older voters, many millennials are unexcited about their choices for president. But if millennials sit this election out, it's Democrats who will feel it most.

A new poll shows Hillary Clinton's massive advantage with millennials closing by 6 percentage points, falling from 68 percent to 62 percent. But this decline didn't exactly translate into increased support for Donald Trump, who only saw a 1 point boost from 20 to 21 percent.

Clearly, many late-breaking millennials are wondering if a third-party vote or staying at home on Election Day is a better choice than Clinton or Trump.

How have Clinton and Trump failed to capture the enthusiasm of the youth vote?

Obviously, there's the Bernie Sanders effect: Millions of young voters were attracted to the Vermont senator's "outsider" campaign. Regardless of whether they agreed with all of his far-left policy prescriptions, millennials saw Sanders as honest and consistent, a person of high character willing to challenge the status quo in politics.

These same youth continue to see Clinton as a corrupt, dishonest friend of Wall Street. That's been reinforced in the last week with new information about abuses at the Clinton Foundation, yet more emails and more evidence that the Democratic party machine was working to bolster Clinton while never giving Sanders a fair shot.

Yet they are turned off by Trump's personal shortcomings, especially his insensitive rhetoric on race and sex.

Neither nominee has made issues of importance to millennials the focus of their campaign, mostly because neither campaign as been especially issue-focused at all. Instead, they're relying on mudslinging and personality politics.

The "issues" that have defined this cycle aren't policy issues at all, but questions about the candidates' backgrounds: Clinton's FBI investigation and email scandal, Trump's tax returns and off-color comments, etc.

If the candidates seriously wanted to court millennial votes, they would have spent more time focusing on millennial pocketbook issues: Obamacare and healthcare costs, the high cost of higher education, federal debt and entitlement reform. In the last days before the election, expect to hear more about these issues as candidates make their closing pitches to American voters.

The bottom line for the millennial vote is turnout. Democrats' rhetorical focus on equality, tolerance and caring for others has attracted many young voters to their brand, if not their policies. A low millennial turnout bodes poorly for Clinton, but even worse for Democrats in tight toss-up races.