Julián Castro, the former housing secretary under Barack Obama and the only Latino candidate in the 2020 presidential race, has ended his bid for the Democratic nomination after struggling to break out in a crowded and diverse field of candidates.

Castro, a third-generation Mexican American, cast himself as a progressive champion of the underserved and under-represented, shaped by his humble beginnings in San Antonio, Texas, where he was raised by his activist mother and rose to be mayor. His exit leaves the field, which began as the most diverse in modern history, without a Latino voice.

“I’ve determined that it simply isn’t our time,” Castro said in video message released by his campaign featuring a montage from his year-long presidential bid that began with a rally in his native San Antonio. “Today it’s with a heavy heart and profound gratitude that I will suspend my campaign for president.”

Castro fought for progressive issues and a nuanced approach to issues of race and diversity. He was one of the first candidates to put forward a policing reform proposal and a sweeping plan on immigration. He placed universal pre-kindergarten at the center of his education plan that called for tuition-free higher education and better pay for teachers.

But the 45-year-old never gained traction in the polls, failing to exceed 2% in national and state polls.

He managed to qualify for the first four Democratic debates – and sparked a party-wide debate over immigration when he sparred with the former Texas congressman Beto O’Rourke on whether to decriminalize border crossings by undocumented migrants, as he proposed – but he did not meet the threshold for the debates that followed. Before the November debate, Castro warned in a fundraising plea that if the campaign was unable to raise more money, he would be forced to end his campaign. The pitch brought in more than $800,000, surpassing the target he set, but he was not able to translate the financial boost into sustained momentum in the polls.

In recent weeks, Castro drew attention for his calls to reform the Democratic nominating process, arguing that opening with contests in Iowa and New Hampshire does not reflect the nation’s changing demographics.

When the California senator Kamala Harris abruptly ended her campaign bid in early December, Castro seethed that she had been treated “very poorly” and was held to an “unfair standard” by the media.

“The media’s flawed formula for ‘electability’ has pushed aside women and candidates of color,” he wrote on Twitter. “Our party’s diversity is our strength.”

Castro first rose to prominence with a rousing speech at the 2012 Democratic national convention, after which he was anointed a rising star. But he struggled to raise money and faced stiff competition from a field of Democrats similarly tipped as the next generation of party leaders.

In 2016, Castro was seen as a potential vice-presidential pick for Hillary Clinton, and is again considered a possible running mate for the eventual nominee, especially as Democrats seek to galvanize Latino voters and make inroads in Texas.

As news of his departure spread, his 2020 rivals began to weigh in, thanking him in particular for the wealth of ideas he brought to the primary contest.

Thank you @JulianCastro for being a powerful voice, for proposing bold and progressive plans, and for using your campaign to help people who need it now. You made this race stronger—and you will continue to be a leader in our party and our country for many years to come. pic.twitter.com/SWlsDC9HcS — Elizabeth Warren (@ewarren) January 2, 2020

I’m going to miss seeing my friend @JulianCastro on the trail. Thank you, Julián, for bringing your ideas and leadership to this race—your voice and campaign were invaluable in sticking up for underrepresented communities and pushing the field forward. pic.twitter.com/qVaMi9X6gd — Cory Booker (@CoryBooker) January 2, 2020

In the nearly four-minute video, Castro offered no hint about future plans.

“I’m not done fighting,” he said. “I’ll keep working towards a nation where everyone counts.

“Ganaremos un día!” he said at the end of the video. “One day we’ll win!”