This article has been updated.

Julián Castro has dropped out of the presidential race.

The announcement came Thursday, as Castro toiled in relative obscurity for months – missing the last two Democratic primary debates and fading from the national conversation.

The former San Antonio mayor, 45, was the only Latino candidate in a Democratic presidential field that once numbered in the 20s and championed progressive policies, such as universal prekindergarten, criminal justice reform, and action on climate change.

“I’m so proud of the campaign we’ve run together,” Castro said to his supporters in a four-minute video released Thursday morning. “We’ve shaped the conversation on so many important issues in this race, stood up for so many vulnerable people, and given a voice to those who are often forgotten. But with only a month until the Iowa caucuses and given the circumstances of this campaign season, I’ve determined that it simply isn’t our time.”

Perhaps the issue for which Castro became most known on the campaign trail and in his few debate cameos was immigration. He sparred with fellow Texan and former U.S. Rep. Beto O’Rourke on whether a section of federal immigration policy should be removed. The argument would help draw a line in the primary between candidates who supported decriminalizing immigration offenses and candidates who espoused less dramatic reforms.

Castro’s few moments in the national spotlight, however, never translated into polling momentum. Castro hovered between 1 and 2 percent in national polling, a shortfall that kept him on the sidelines for the past two debates and encapsulated his struggle for name recognition. In a primary dominated by three frontrunners – former Vice President Joe Biden and U.S. Sens. Elizabeth Warren and Bernie Sanders – Castro never cracked the upper echelon of candidates. He openly chafed at the idea that South Bend, Indiana, Mayor Pete Buttigieg was earning more media attention than his campaign was despite Buttigieg’s poor polling with minorities.

Castro’s campaign often appealed to diversity and those who live in the margins of society, including people of color, undocumented immigrants, and the transgender community.

In recent months, the former U.S. Department of Housing and Urban Development secretary had voiced his displeasure with the Democratic National Committee’s process for selecting a nominee, which began with the Iowa caucuses and the New Hampshire primaries, as has been the case for nearly 50 years.

But those states, many have argued, do not reflect the growing diversity in the Democratic Party and aren’t even reliably Democratic.

Iowa ultimately went to Donald Trump in the 2016 general election, and Hillary Clinton narrowly won New Hampshire. Neither state is demographically diverse, with 85 percent and 90 percent non-Hispanic white populations respectively, according to the U.S. Census.

South Texas Democratic strategist Colin Strother said the DNC’s process, which winnowed an unusually large candidate pool with increasingly higher thresholds for fundraising and polling, doomed Castro and other candidates of color.

“Campaigns like Julián’s, [U.S. Sen. Kamala Harris’, and U.S. Sen. Cory] Booker’s, instead of building their campaigns naturally and organically, they had to spend money trying to get people to give them a dollar,” Strother said. “I’d hate to see the [return on investment] on that. … The process was fatally flawed for a candidate like Julián.”

However, Castro’s withdrawal from the presidential race far from spells the end for his political career, Strother said. At age 45, Castro remains a likely pick for the eventual nominee’s running mate, especially if it is one of the three white septuagenarians at the front of the race, he said.

“I think he’s a shoo-in for the VP shortlist particularly when you look at demographics of two of the states we need to flip, which are Florida and Texas,” he said, adding Castro would be an automatic cabinet pick if he’s not tapped as the nominee’s running mate. “He would also have to be strongly considered for an ambassadorship, including to the United Nations. He brings a lot to the table. He demonstrated that well during the primary. I certainly don’t think we’ve seen the last of Julián Castro.”

Castro’s detailed policy papers, ranging from animal rights to a Marshall Plan for Central America, garnered attention from politicos throughout the country but were not enough to propel him into the national consciousness. Although he ultimately did not win the support he needed to reach the primaries, his imprint will still be felt on the campaign and his influence has helped dictate policy debates among the highest-polling Democrats, said Texas Rep. Diego Bernal (D-San Antonio), who has known Castro since middle school.

Bernal, an avid music fan, likened Castro’s influence to hip-hop. Many of mainstream rap’s most popular figures often credit lesser-known artists for inspiring their careers and songwriting, he said.

“For a lot of people, Julián is their favorite rapper’s favorite rapper,” Bernal said.

For Mayor Ron Nirenberg, Castro’s entry into the presidential race marked a historic milestone for the area – as San Antonio’s first presidential candidate. Candidate Castro, he said, brought a message of both optimism and inclusion to the race.

“He changed the conversation fundamentally,” Nirenberg said. “In doing so, Julián represented our city and our country very well. His most impactful days are clearly still ahead.”

Castro entered the presidential race in January 2019 in front of thousands of supporters near the West Side neighborhood where he and his twin brother Joaquin, a U.S. congressman, grew up. The faces in the crowd reflected the diversity Castro sought to cultivate. In the Trump era, Castro said at the time, the idea of the American Dream appeared to be withering for certain communities.

“We are going to make sure that the promise of America is available to everyone in this country,” he said in front of the gathered crowd. “When we want change, we don’t wait for change, we work for it.”

In his video message to supporters Thursday, Castro said he’s not done fighting to restore the American Dream. It wasn’t immediately clear what that would entail.

“To all who have been inspired by our campaign, especially our young people, keep reaching for your dreams and keep fighting for what you believe in,” he said. “¡Ganaremos un día! (One day we’ll win!)”