Story highlights Peter Hart collaborates on the NBC-Wall Street Journal polls

He says Clinton needs to open up about what drives her during the debates

The Axe Files, featuring David Axelrod, is a podcast distributed by CNN and produced at the University of Chicago Institute of Politics. The author works at the institute.

Chicago (CNN) Veteran pollster Peter Hart rates Hillary Clinton as a seven-to-one favorite to win the presidency and sees a narrow path for Donald Trump, opened for him by the other candidates on the ballot.

"There are many problems (for Trump) ... the minorities, then you look at women and you look at millennials, all those are disqualifying for winning the presidency," Hart told David Axelrod on "The Axe Files" podcast, produced by the University of Chicago Institute of Politics and CNN. "But against it you've got a third-party candidate (Libertarian nominee Gary Johnson) and a fourth-party candidate (Green Party nominee Jill Stein) and you have to watch that very carefully. If that vote stays up in the 15% level, then does Trump have enough room to beat Hillary Clinton? Yes, he does."

Hart said to slam the door, Clinton needs to be more revealing in the upcoming debates about what, beyond personal ambition, drives her to seek the presidency.

"People want to see who she is and what she's going to be like (as president)," he said. "All of the integrity questions create the doubt and uncertainty. ... What are her motivations?

"I think if I asked that question in a focus group, I would get a very negative answer. She can talk about all of the programs she has, but what she really needs to talk about are the fights that she wants to take on."

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