Democratic presidential candidate Bernie Sanders is behind in the delegate count by near-insurmountable numbers. But he makes the case that he's a better nominee for November because he polls better than Hillary Clinton in head-to-head matchups against presumptive Republican nominee Donald Trump.

Sanders made the point again during the May 29 edition of NBC's "Meet the Press."

"Right now," Sanders said, "in every major poll, national poll and statewide poll done in the last month, six weeks, we are defeating Trump often by big numbers, and always at a larger margin than Secretary Clinton is."

We checked a similar assertion by Sanders in March and found it to be Mostly True. But there have been new polls since then, so we decided to take a new look.

As we did previously, we looked at polls taken during the last six weeks that are listed on RealClearPolitics.com and that tested Trump's support against both Clinton and Sanders.

Sanders is correct that he fares better against Trump than Clinton does in every poll over the past six weeks — more than 6 points better than Clinton, on average.

And Sanders is beating Trump by an average of 12 points in these eight polls, so "big numbers" seems like a reasonable description for Sanders to use.

Case closed? Not quite, say polling experts.

Clinton has been scrutinized and attacked as a public figure for a quarter century, but Sanders — even after running for president for a year — is a relatively new figure to voters nationally. So while a lot of voters' minds are already made up about Clinton based on her long history in the public eye, it remains to be seen how open potential voters will be to supporting Sanders once Republicans start airing negative attacks, especially ones that note his identification as a democratic socialist. (We have previously reported that, according to polls, being a socialist is a less attractive quality for voters than being an atheist.)

Kerwin Swint, a political scientist at Kennesaw State University, told PolitiFact Georgia that Sanders shows up so strongly in head-to-head polls because Trump and Clinton have such high negatives.

"General election polls don't mean much until the conventions are over and you get to late summer or early fall," Swint said. "A lot of voters don't look at Sanders as a legitimate threat. It's almost like he's an imaginary candidate."

In addition, early polls do not zero in on "likely voters," as polls later in the campaign do, Steven S. Smith, a Washington University political scientist and a specialist in public opinion, told PolitiFact when we previously checked a similar statement by Sanders. This could matter, given Sanders' high rates of support among college students and younger voters, who have not yet demonstrated a long track record of voting.

"If Sanders draws disproportionately from people who are not likely to vote, which is a reasonable speculation at this point, then his support may be somewhat overstated in some comparisons," Smith said.

And it's worth adding that, as "Meet the Press" host Chuck Todd noted, Clinton can be expected to poll better against Trump after she officially secures the nomination and many former Sanders supporters come to her side.

Our ruling

On the numbers, Sanders is correct: In the past six weeks' worth of polls, Sanders fares 6 points better against Trump than Clinton does, and he beats Trump by double digits on average. Still, polling experts caution that polls this far away from Election Day are not entirely reliable, and they add that Sanders hasn't been exposed to the same degree of negative attacks as Clinton has. We rate the claim Mostly True.

PolitiFact.com is a project operated by the Tampa Bay Times, in which reporters and editors from the Times and affiliated media outlets "fact-check statements by members of Congress, the White House, lobbyists and interest groups." The Star Tribune opinion pages periodically republish these reports.