Former Vice President Joe Biden must be able to surpass the combined polling numbers of rivals Sens. Bernie Sanders, I-Vt., and Elizabeth Warren, D-Mass., in order to politically survive in the long term, according to Greg Gutfeld.

After a Monmouth University poll showed Biden trailing the two lawmakers, but within the margin of error -- essentially a dead heat -- Gutfeld said Tuesday on "The Five" that the Delaware Democrat needs to get back up to 40 percentage points' worth of support.

"I think these polls have a self-fulfilling prophecy," he said, noting the poll had Sanders and Warren at 20 percent support each, with the longtime frontrunner at 19 percent.

BIDEN PLUNGES, TIED WITH WARREN AND SANDERS IN NEW NATIONAL POLL

"Biden needs to get a number that's larger than Bernie and Liz combined before Bernie or Liz drops out -- because if one of them drops out, then the other one absorbs that person."

Gutfeld added that both Warren and Sanders have laid claim to the progressive wing of the primary, while Biden has remained more centrist.

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The survey – released Monday – showed the former vice president plunged 13 percentage points from where he stood in June. Sanders rose six points from the June poll, with Warren rising five points.

The Biden campaign took aim at the survey, telling reporters, "This poll is an outlier that is contradicted by every measure of the national average."

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“The main takeaway from this poll is that the Democratic race has become volatile,” Monmouth University Polling Institute Director Patrick Murray said.

Fox News' Paul Steinhauser contributed to this report.