A new national poll from Quinnipiac University shows President Trump trailing each of six Democratic candidates in potential head-to-head contests and calls Joe Biden's advantage of "landslide proportions."

The Democrats' lead ranges from five points for Cory Booker and Pete Buttigieg to 13 points for Biden. In between, Bernie Sanders leads Mr. Trump by nine points, Kamala Harris by eight, and Elizabeth Warren by seven.

Interestingly, while Biden beats Mr. Trump by a landslide in the Quinnipiac poll, his lead among his Democratic competitors has narrowed since April. One Iowa Democrat CBS News spoke to said she's happy to have a lot of great options but some think maybe a little too many.

The president and former vice president traded sharp words in Iowa Tuesday where, as CBS News' Ed O'Keefe reports, it appears like the two are already campaigning as if it's November 2020. Both have repeatedly traded barbs since the former vice president jumped into the 2020 race, but as the Quinnipiac indicates, Biden isn't the only Democrat the president has to worry about.

"I'd rather run against, I think, Biden than anybody. I think he's the weakest mentally. And I like running against people that are weak mentally. I think Joe is the weakest up here," Mr. Trump said.

The president's focus on Biden is strategic. CBS News has learned that polling conducted by the Trump campaign shows the president trailing the former VP in several key states and Biden's approach seemed to resonate.

"He thinks these tariffs are being paid by China, just like he thinks Mexico is building the wall," Biden said to applause Tuesday.



But Iowa voters also say they're hungry for policy proposals.

"I don't vote for a persona, I vote for what are you going to do," one Iowa voter said.

Mr. Trump knows voters aren't yet sold on Biden. The president's campaign also believes Elizabeth Warren is gaining strength, and sees a path for Bernie Sanders. So for now, President Trump is an equal opportunity opponent.