The data, from the Harvard University Institute of Politics, shows Clinton gaining 6 points since the group’s pre-convention polling. The most significant boost came to her favorability, which jumped significantly over the past three months while Trump’s high unfavorable rating has held firm.

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That 28-point lead is higher than Obama's 19-point lead over Republican Mitt Romney in the Harvard poll released two weeks before the 2012 presidential election.

The Democratic nominee went from a net favorability rating of minus 29 this summer to minus 13 in the latest data. Among likely voters in the age group, she fared even better, with 48 percent viewing her favorably and 51 percent unfavorably.

Trump’s net favorability has barely moved since Harvard started polling in April. His rating of minus 60 has shifted to minus 54, with 22 percent of millennials viewing him favorably and 76 percent viewing him unfavorably.