A Monmouth University poll released Monday showed Sens. Bernie Sanders and Elizabeth Warren tied for first place in the 2020 Democratic presidential primary race, while former Vice President Joe Biden fell to second as his support dropped 13 points since June.

The survey found Sanders and Warren are even at 20 percent support from registered Democrats and Democratic-leaning independent voters. Sanders saw the largest jump in support of any candidate in the survey, gaining six points since Monmouth's June poll.

Biden, who leads most national surveys, polled at 19 percent support, down from 32 percent in June.

"It's important to keep in mind this is just one snapshot from one poll," Patrick Murray, director of the independent Monmouth University Polling Institute, said in a statement. "But it does raise warning signs of increased churning in the Democratic nomination contest now that voters are starting to pay closer attention."

The survey has a 5.7 percent margin of error and a sample size of 298 Democratic and Democratic-leaning independent voters.

As Washington Post reporter Dave Weigel highlighted in his response to the new poll, it is perhaps Biden's substantial drop that warrants the most attention.

The poll comes as both Sanders and Warren are drawing large and enthusiastic crowds across the nation as they make the case for their progressive platforms.

On Sunday, Bloomberg reported, Warren attracted the largest audience of her presidential campaign as an estimated 15,000 attended her rally in Seattle. During the event, the Massachusetts senator touted her call for a two percent wealth tax on Americans with more than $50 million in assets.

Sanders, meanwhile, drew a large crowd in the deep red state of Kentucky, where he rallied with striking AT&T workers and called out Senate Majority Leader Mitch McConnell (R-Ky.) for obstructing minimum wage legislation.

The Vermont senator's campaign was quick to tout the Monmouth survey as evidence of a Sanders surge.

In the campaign's BERN Notice newsletter, Sanders speechwriter David Sirota noted, in addition to the senator's overall gains, his growing support among people of color in the new survey.

"The poll shows Bernie is now the candidate with the largest amount of support from people of color," said Sirota. "Compared to Monmouth's June poll, Biden has dropped 14 points among people of color, while Bernie has gained seven points among people of color—the biggest gain of any candidate."