"Not today," Warren continued. "I want to take a little time to think a little more. I've been spending a lot of time right now on the question of suspending and making sure this works the best we can for our staff, our team and our volunteers."

The scene in Warren’s neighborhood was a stark departure from two days prior, when hundreds of Warren’s supporters lined the street to watch her walk to cast a ballot in the Massachusetts primary. Warren came in third in her home state — a devastating blow for the once-promising presidential candidate who failed to win any states on the electoral map.

Warren expressed regret that after a year on the trail and a record number of women candidates, the race had narrowed to two white men — Biden and Sanders.

"I was told at the beginning of this whole undertaking, that there are two lanes. A progressive lane that Bernie Sanders is the incumbent for and a moderate lane that Joe Biden is the incumbent for, and there's no room for anyone else in this. I thought that wasn't right. But evidently I was wrong," Warren said.

While Warren and Sanders are ideologically similar and had been friends before the 2020 campaign, their relationship frayed over the course of the campaign, which could impact her endorsement.

Things came to a boiling point earlier this year, when Warren said Sanders told her in a private meeting he did not believe a woman could beat Donald Trump in 2020. Sanders denied making the comment. The spat came to a head after a primary debate, when Warren approached Sanders on stage and said "I think you called me a liar on national TV."

More recently, Sanders sought to beat Warren on her home turf in Massachusetts on Super Tuesday, a move which frustrated some Warren allies. Sanders held two Massachusetts rallies in the days leading up to Super Tuesday that drew a collective 15,000 people, while Warren hadn't held an event in the state for months. Sanders' rally on the Boston Common was only 6 miles away from her Cambridge home.

Biden went on to win Massachusetts, and both of the cities where Sanders appeared in person.

The rift in the progressive wing of the party sits in stark contrast to the way moderates have coalesced around Biden in recent days, providing momentum that allowed the former vice president to dominate the Super Tuesday electoral map. In the days leading up to Super Tuesday, Pete Buttigieg and Amy Klobuchar dropped out of the race and threw their support behind the former vice president, as did former Rep. Beto O'Rourke, who ended his campaign months earlier.

"One of the hardest parts of this is all those pinky promises and all those little girls who are going to have to wait four more years," Warren said, a reference to the pinky promises she made with young girls she met on the trail.