Washington — Senator Elizabeth Warren is ending her presidential campaign after failing to win any primary contests and placing third in her home state of Massachusetts on Super Tuesday. She informed her staff in a conference call Thursday morning before an emotional afternoon press conference outside her home in Cambridge, Massachusetts.

"I say this with a deep sense of gratitude for every single person who got in this fight," Warren told reporters. "I will not be running for president in 2020, but I guarantee I will stay in the fight for the hardworking folks across this country who've gotten the short end of the stick."

Her exit from the race clears the way for a head-to-head matchup between Joe Biden and Bernie Sanders, the two candidates who emerged from Super Tuesday atop the delegate race. Warren spoke to Biden on Wednesday, according to a source with knowledge of the conversation.

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Warren said she needed "space" to think about her endorsement, saying she would not make a decision "right now."

"Let's take a deep breath and spend a little time on that," Warren said about who her supporters should turn to now that she has dropped out of the race.

Senator Elizabeth Warren talks to reporters outside her house about the end of her campaign for president in Cambridge, Massachusetts, on March 5, 2020. BRIAN SNYDER / REUTERS

As the field has essentially narrowed to a two-man race, Warren became emotional as she discussed her disappointment that a woman would not be the nominee.

"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. She had made a practice of making pinky promises with little girls who attended her campaign events, saying she was running for president "because that's what girls do."

Warren also briefly touched upon the impact sexism had on her campaign.

"If you say, 'Yeah, there was sexism in this race,' everyone says, 'Whiner!' And if you say, 'No, there was no sexism,' about a bajillion women think, 'What planet do you live on?'" Warren said.

In a call with campaign staff Thursday morning, Warren said her campaign "has made a lasting difference."

"What we have done — and the ideas we have launched into the world, the way we have fought this fight, the relationships we have built — will carry through, carry through for the rest of this election, and the one after that, and the one after that," Warren said in the call, according to her campaign.

The Massachusetts senator proved to be an incisive debater, and her attacks on Michael Bloomberg punctured holes in his argument that he was the most electable candidate against President Trump.

Warren had a fervent base, but she failed to gain a diverse coalition of support. Across the Super Tuesday states, exit poll data showed four in 10 Democratic primary voters who backed her identified as "very liberal," similar to the percentage of Sanders supporters who identify that way. Sixty-six percent of her supporters were women, and 82% were white. Sixty-nine percent of Warren supporters had college degrees, including 39% with advanced degrees, making her supporters the most educated of the top candidates.

Warren declared her candidacy in January 2019, and worked to distinguish her campaign with her thorough policy plans. However, her support for Medicare for All and assertion that implementing the plan would not include raising taxes on the middle class put off some more moderate Democrats.

She finished in third place in the Iowa caucuses, and fell to fourth in New Hampshire, her neighboring state. She initially resisted dropping out of the race after her disappointing showing on Super Tuesday, choosing to talk "to her team to assess the path forward" the day after.

Her third-place finish in Massachusetts raised questions about how long she could remain as a candidate. Speaking to supporters on Tuesday evening, Warren indicated that she did not plan to drop out.

"My name is Elizabeth Warren, and I'm the woman who's going to beat Donald Trump," Warren said in Detroit. She urged voters not to listen to prognostications from pundits, but instead to vote with their hearts.

"Prediction has been a terrible business, and the pundits have gotten it wrong over and over," Warren said.

In a memo to staff, Warren campaign manager Roger Lau said that the team was "disappointed in the results."

"Last night, we fell well short of viability goals and projections, and we are disappointed in the results. We're still waiting for more results to come in to get a better sense of the final delegate math. And we also all know the race has been extremely volatile in recent weeks and days with frontrunners changing at a pretty rapid pace," Lau said in the memo. "But we are obviously disappointed."

Several former presidential candidates have endorsed Biden, including Bloomberg, Amy Klobuchar, Pete Buttigieg and Beto O'Rourke.

Biden picked up wins in Massachusetts, Virginia, North Carolina, Alabama, Arkansas, Tennessee, Minnesota, Oklahoma and Texas, while Sanders won in Colorado, Utah and his home state of Vermont. Sanders is also currently leading in California as votes continue to be counted.

Ed O'Keefe, Zak Hudak and Caitlin Huey-Burns contributed reporting.