Trump campaign is losing his most reliable 2016 voters to Biden: CNN analyst
Donald Trump/Joe Biden -- AFP/Biden Facebook page

With only days before the first presidential debate, President Donald Trump's weakness among a key demographic that elected him in 2016 is haunting his re-election effort, according to a new analysis by CNN's Harry Enten.

"President Donald Trump heads into the debate trailing former Vice President Joe Biden. Trump is the first incumbent to be losing in the polls at this point since George H.W. Bush in 1992," Enten noted. "Trump's obvious goal for the debate is to try and win back some of the white voters without a college degree that he's clearly lost since 2016."

Enten based his analysis on nine polls from eight pollsters that have been released since the convention.

"Trump is winning by about 21 points among Whites without a college degree in an average of those polls. That may seem like a lot, but remember that Trump led among this group by about 30 points in the final pre-election polls in 2016," Enten explained. "Keep in mind, we're making an apples-to-apples comparison here. Even if the polls are off by a similar margin as they were in 2016, this exercise takes that into account. There's real movement going on here among Whites without a college degree."

White voters without degrees make up the majority of voters in Michigan, Pennsylvania and Wisconsin -- three states Trump narrowly carried in 2016.

"Not surprisingly, Biden's position in these states has significantly improved from where Clinton ended up. He's got a 5- to 7-point advantages in all of these states," Enten noted. "We see similar big shifts toward Biden compared to Clinton in other key states in the region: Iowa and Ohio. Biden's about even in Iowa and slightly ahead in Ohio, despite Clinton losing them by 9 and 8 points respectively. Again, both states have a lot of White voters without a college degree."

"The question heading into the debates is whether Trump can do anything to knock those voters away from Biden. If he cannot, Biden's likely to be the next president," Enten concluded.