BOSTON — Sen. Elizabeth Warren is in a fight to win her home state of Massachusetts, according to a new poll released Friday that shows her down 1 percentage point to national frontrunner Sen. Bernie Sanders in the state's Democratic presidential primary.

The poll, conducted by YouGov for the University of Massachusetts Lowell Center for Public Opinion, found Warren with support of 20% of likely Democratic primary voters in Massachusetts, trailing Sanders' 21%.

They are followed by former South Bend, Indiana, Mayor Pete Buttgieg, 15%, former Vice President Joe Biden, 14%, former New York Mayor Mike Bloomberg, 12%, Minnesota Sen. Amy Klobuchar, 9%, Rep. Tulsi Gabbard, 3%, and businessman Tom Steyer, 2%. Four percent said they were undecided.

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The poll, an online survey of 450 voters, was taken from Feb. 12 to Feb. 19 – before Warren's standout performance in Wednesday's Democratic debate in Las Vegas. Sanders' lead is within the poll's 6.1% margin of error.

"What we're seeing when we look at Massachusetts and other Super Tuesday states is that Sanders is in that range of 21% to about 25% in all of these states," Joshua Dyck, director of the UMASS Lowell Center for Public Opinion, said. "So, Sanders is showing the strength of a national frontrunner who isn't pulling away but is basically polling well everywhere."

Dyck said Warren is competing for first place in Massachusetts because of her home-state advantage and its liberal makeup.

"But she's also contending with the fact that liberal voters, progressive voters, and young voters who are drawn to her campaign are also drawn to Sen. Sanders' campaign," he said. "There's a real battle for a similar type of voter. That's been her difficulty: As Sanders has emerged as a frontrunner, she's had to distinguish herself and find strength with other voters."

Massachusetts is among 14 states that vote on March 3 – known as Super Tuesday – when about 30% of the Democratic electorate goes to the polls. Early voting in Massachusetts begins Monday.

The poll found Sanders has a sizable lead over Warren in support among voters 45 years old or younger, with the Vermont senator earning 31% to Warren's 21%. Buttigieg is third in that category at 18%.

Warren leads among older Massachusetts voters 45 years or older, with 19%, followed by Sanders, 16%, Biden, 14%, Bloomberg, 14%, and Buttigieg, 13%.

"The open question right now is she clearly won the debate on Wednesday night, or at least had the big moments in taking down Michael Bloomberg," Dyck said. "She's got a week and a half until Super Tuesday. What happens with the momentum in her campaign from this debate performance?"

Warren, a two-term senator and former Harvard law professor, won her first race in 2012 against incumbent Republican Scott Brown by a margin of 54% to 46%. She won reelection easily in 2018 with more than 60% of the vote.

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This weekend, Warren has planned door-to-door canvassing in Massachusetts that will include deploying two members of Congress from Massachusetts, Reps. Lori Trahan and Jim McGovern, as well as state Attorney General Maura Healey. Rep. Ayanna Pressley, D-Mass., a top Warren surrogate, will be campaigning for Warren in South Carolina.

Warren, the one-time polling leader nationally, saw her numbers drop in November with a rocky rollout of her plan to pay for Medicare for All. She finished third in the Iowa caucuses and fourth in her neighboring state of New Hampshire with 9.2% of the vote.

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Reach Joey Garrison and on Twitter @Joeygarrison.