Sen. Elizabeth Warren of Massachusetts on Thursday announced she was suspending her presidential campaign after failing to win any of the first 18 states to vote.

People left thank-you notes around Warren's framed photo on the wall of tenured professors at Harvard Law School, where she used to teach.

"An inspiration who deserved better than we could deliver," one note said, adding "pinky promise" — a reference to Warren performing the gesture with young girls she met on the campaign trail promising to become the first female president.

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People left thank-you notes near Sen. Elizabeth Warren's photo on the wall of tenured professors at Harvard Law School on Thursday after the Massachusetts lawmaker announced the end of her presidential campaign.

Warren maintained a strong standing in polls for much of the race and was briefly a frontrunner but failed to place first in any of the first 18 states after progressives rallied behind Sen. Bernie Sanders of Vermont and moderates threw their support behind former Vice President Joe Biden.

On Super Tuesday, the senator came in third in her home state of Massachusetts and fourth in Oklahoma, where she grew up. She announced the end of her presidential bid in a call to her campaign staff.

"We didn't reach our goal, but what we have done together — what you have done — has made a lasting difference," she said, according to a memo of the call. "It's not the scale of the difference we wanted to make, but it matters — and the changes will have ripples for years to come."

Following the news that she was suspending her campaign, people began to leave Post-it notes thanking the senator for her "bravery and persistence" in her presidential run.

"An inspiration who deserved better than we could deliver," one note said, adding "pinky promise" — a reference to Warren performing the gesture with young girls she met on the campaign trail promising to become the first female president.

"One of the hardest parts of this is all those ... little girls who are going to have to wait four more years," Warren told reporters in Boston after ending her campaign.

Warren entered the 2020 race with a dedication to greet every person who supported her campaign face-to-face — and spent hours at a time to take selfies with folks at her rallies and fundraisers. As a former teacher and professor, she had a strong stance on education and had a plan — as she did with many other issues — to cancel student debt and improve childcare.

She was the last serious female candidate in the Democratic pool after Sen. Kirsten Gillibrand of New York, Sen. Kamala Harris of California, Sen. Amy Klobuchar of Minnesota, and the author Marianne Williamson all exited the race.

Rep. Tulsi Gabbard of Hawaii is still campaigning but barely registers in the polls and carries only a few delegates.