Hillary Clinton hoped that Bernie Sanders's endorsement would lead to millions of young people supporting her campaign, but that hasn't worked out.

Monmouth University produced a poll on Monday showing the overwhelming majority of millennials were unaffected by Sanders's endorsement.

According to the poll, 63 percent of likely voters ages 18-34 said that the support from Sanders had no impact on them. Another 13 percent said they were less likely to support Clinton, and just 23 percent said it made them more likely to support the former first lady.

Older generations had no opinion of the endorsement, which makes sense considering most active Sanders supporters tended to be millennials.

Overall, Clinton had a small lead among likely voters, 45 percent to Trump's 43 percent, within the margin of error. Libertarian Gary Johnson and Green Jill Stein had 5 percent and 1 percent, respectively.