Democratic presidential candidate Julián Castro announced the end to his campaign on Thursday.

“It’s with profound gratitude to all of our supporters that I suspend my campaign for president today,” Castro tweeted. “I’m so proud of everything we’ve accomplished together. I’m going to keep fighting for an America where everyone counts—I hope you’ll join me in that fight.”

The former Obama administration Housing and Urban Development secretary announced the conclusion of his White House bid after falling short in polling, fundraising, and eventually failing to make the November and December debate stages. He was one of the first Democrats to declare his candidacy back in January and announced in his hometown of San Antonio, Texas, where he previously served as councilman and later as one of the youngest mayors of a top 50 American city.

Sen. Elizabeth Warren, who has had a close relationship with Castro during the campaign, tweeted thanks to her fellow candidate for being “a powerful voice.”

Castro, the first Mexican-American to have sought the presidency, was at times progressive in his policy proposals, pushing for the decriminalization of border crossings, reparations for the descendants of African-American slaves and calling for the legalization of marijuana.

Castro has also held moderate positions on major topics in the Democratic field, such as opposing the elimination of private insurance for “Medicare for All” and infamously tousling with former Vice President Joe Biden at the September debate co-hosted by ABC News and Univision — when he argued that under Biden’s health care plan people would have to buy in in order to be enrolled after losing their insurance.

Although consistently one of the first candidates to comment or call for controversial actions, Castro still faced many headwinds as a candidate with limited name recognition.

For example, Castro was one of the first candidates to say Congress shouldn’t take impeachment inquiry of President Donald Trump off the table back in April 2019 after the redacted release of special counsel Robert Mueller’s report on Russian interference in the 2016 election and potential obstruction of justice.

Following months of low polling results in states like Iowa and New Hampshire, Castro was also one of the only candidates calling for a re-ordering of primary states in future presidential elections.

“If we truly value black women, for instance, and we keep telling them that they’re the key to our success, in places like Louisiana and Alabama and that they’re going to be key in 2020, then why do we start the most important nominating process in our whole party, the presidential nominating process in two states that hardly have any black people in them. Doesn’t make any sense, ” Castro told reporters in Waterloo, Iowa as recently as early December.

With the departure of Sen. Kamala Harris, D-Calif., from the presidential race, Castro was also one of the first to point out the lack of diversity left in the Democratic field, telling reporters from a pre-planned visit to Harris’ home state of California that there was “a renewed sense out there that our primaries need better representation. Especially because we’re headed towards the debate, that will have no people of color on the stage.”

Castro made the first four debate stages, but failed to gather four qualifying polls to make the November and December debate stages.

Castro’s campaign announced they had their biggest fundraising day in the month of November during the night of the MSNBC/Washington Post debate, raising more that night than he did during the last two debates he had participated in. The Castro campaign later announced they had reached the donor threshold for the December debate after a surge of donations raised over $360,000 in the days following Sen. Harris’ departure from the race.

However, quarter to quarter Castro wasn’t able to match the overall fundraising totals of some of the frontrunners in the race. He pulled in a dismal $3.5 million in the third quarter, leaving his campaign with the least cash on hand compared to other top 11 candidates — only $672,000.

About a week after the release of his third-quarter numbers, Castro made a dramatic fundraising plea to raise $800,000 by Oct. 31 in order to stay in the race, saying in an email to supporters that if the campaign didn’t reach the goal, he would “have no choice but to end my race for President.” The Castro campaign eventually made the fundraising goal late into the night on Oct. 31st, saying they raised a total of $1 million in October.

However, just days after announcing the success of his fundraising plea the Castro campaign announced they had laid off staff in New Hampshire and South Carolina. At the time, Castro’s spokesperson Sawyer Hackett said they would be shifting focus to Iowa, Nevada and Texas.

Castro initially reached the national stage when he was the first Hispanic to deliver the keynote address at the 2012 Democratic National Convention in Charlotte, North Carolina. Castro was later shortlisted and vetted as a Vice-Presidential candidate during former Secretary of State Hillary Clinton’s 2016 presidential campaign.

Clinton eventually chose Virginia Sen. Tim Kaine, with Castro campaigning for Clinton as a surrogate.