With three days until the next scheduled Democratic presidential nomination debate, a new national poll indicates former Vice President Joe Biden and Sen. Bernie Sanders of Vermont are leading the rest of the still large field of White House hopefuls.

Biden – who has remained at the top of nearly every national poll since even before he declared his candidacy in late April -- stands at 24 percent among Democrats and Democratic-leaning independent voters in a NPR/PBSNewsHour/Marist poll released Monday.

Sanders, the populist senator from Vermont who is making his second straight run for the Democratic nomination, is at 22 percent. Biden’s slight 2-point edge is within the survey’s sampling error.

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Massachusetts Sen. Elizabeth Warren – another top-tier contender who has seen her poll numbers slip the past two months -- stands at 17 percent in the poll. And South Bend, Indiana Mayor Pete Buttigieg – a onetime long-shot who’s soared in recent months in surveys in the early voting states of Iowa and New Hampshire – registers at 13 percent support.

According to the poll, tech entrepreneur Andrew Yang is at 5 percent, with Sens. Cory Booker of New Jersey, Amy Klobuchar of Minnesota and former New York City Mayor Mike Bloomberg each at 4 percent. Sen. Michael Bennet of Colorado, Rep. Tulsi Gabbard of Hawaii, and former Obama housing secretary and former San Antonio, Texas Mayor Julian Castro stand at 1 percent. Every other candidate else registered at less than 1 percent.

The poll indicates that with a month and a half to go until the Iowa caucuses kick off the presidential nominating calendar, just over three-quarters of those questioned said they could change their minds on who they are currently supporting.

Marist Institute for Public Opinion director Lee Miringoff – who conducted the poll – noted that even though Biden’s consistently led the national polls, there’s been plenty of fluidity in the crucial early-state surveys.

"I think we're looking at the last surge" for who could win, Miringoff said.

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The NPR/PBSNewsHour/Marist poll was released a day after a new national Fox News Poll indicated Biden at 30 percent in the Democratic nomination race, with Sanders at 20 percent and Warren in third at 13 percent. Buttigieg registered at 7 percent, with Klobuchar and Bloomberg each at 5 percent and everyone else at 3 percent or less.

While Biden and Sanders' numbers were basically unchanged from the previous Fox News survey – which was conducted at the end of October – Warren dropped 8 percentage points.

The NPR/PBSNewsHour/Marist poll was conducted Dec 9-11, with 1,508 registered voters nationwide, including 704 Democrats and Democratic-leaning independents, questioned by live telephone operators. The margin of error for questions on the Democratic presidential primary is plus or minus 5.4 percentage points.