SPRINGFIELD, Mass. (AP) — U.S. Senate candidate Elizabeth Warren will be the only Democrat on the party’s primary election ballot in September.

Marisa DeFranco, the other Democrat in the race, fell far short of winning the support of at least 15 percent of the more than 3,500 delegates to the state party convention Saturday in Springfield. The long-shot candidate needed to meet that threshold to earn a spot on the ballot.

Warren won the party endorsement with more than 95 percent of the vote. She becomes the presumptive Democratic nominee to face Republican Sen. Scott Brown in November.

She told delegates before the vote that she wouldn’t back down from Brown. She said he would rather attack her family than defend his record in Congress.

WBZ NewsRadio 1030′s Lana Jones reports

DeFranco, an immigration attorney, had urged delegates to support a “good and healthy primary.”

Copyright 2012 The Associated Press.