Castro ending his bid leaves the Democratic primary field without a Latino candidate, and his exit comes one month before the Iowa caucuses.

It’s with profound gratitude to all of our supporters that I suspend my campaign for president today.

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. pic.twitter.com/jXQLJa3AdC

— Julián Castro (@JulianCastro) January 2, 2020

The Obama-era housing secretary and former mayor of San Antonio launched his campaign last January but struggled to gain traction in the crowded Democratic field. His only notable congressional endorsements came from his brother, campaign chairman and Congressional Hispanic Caucus Chairman Joaquin Castro, as well as freshman Texas Rep. Colin Allred, who worked for Castro at HUD and received early backing from Castro during his 2018 race.

Castro often distinguished himself as the “first” candidate and sought to move the field left on a host of issues — including by visiting Flint, Mich., and Puerto Rico on the trail; releasing policies on immigration, indigenous communities and lead exposure; and supporting the impeachment of President Donald Trump. He also made waves by calling for the decriminalization of illegal border crossings, a position he was later followed on by some others in the field. But Castro rarely received attention for jumping out in front.

Still, Castro says in Thursday’s video, “I’m so proud of the campaign we’ve run together. We’ve shaped the conversation on so many important issues in this race, stood up for the most vulnerable people and given a voice to those who are often forgotten.”

He grew his small operation — for a time, his communications shop was run solely by a senior aide — into a campaign that qualified for four nationally televised debates, and he outlasted senators, congressmen and current and former governors. But he was unable to seriously compete with the top tier of candidates, some of whom began the race with higher name identification, built-out email lists and well-stocked campaign treasuries from past elections.

Castro did generate some shining moments on the Democratic debate stages, including challenging fellow Texan Beto O’Rourke on immigration in Miami, highlighting Atatiana Jefferson, a black woman who was killed inside her home by a white Texas police officer in October, and calling out police gun violence in Ohio.

But those moments never translated into big movement in the Democratic primary polls for Castro. And his swing-and-miss at Joe Biden in Houston — when he asked the former vice president if he had forgotten what he had said two minutes ago — cost him some support. Rep. Vicente Gonzalez of Texas pulled his endorsement from Castro after that, backing Biden instead.

He failed to meet the polling threshold for the two most recent primary debates, and was likely to miss the next debate later this month as well.

Castro made no immediate mention of throwing his support behind one of his former rivals, and did not outline his immediate plans. But “I’m not done fighting,” he vows in the video, adding that “I’ll keep working towards a nation where everyone counts, a nation where everyone can get a good job, good health care and a decent place to live.”

Castro is the latest candidate of color to end their presidential campaign, following Sen. Kamala Harris’ exit last month, and his departure is sure to revive concerns about diversity in the Democratic primary — he was extremely vocal in criticizing the way minority candidates are covered and treated on the day that Harris dropped out.

Harris cited fundraising struggles as part of her decision to exit the race, an issue Castro alluded to as well when he issued a plea to voters earlier in the fall warning that that his campaign would be “silenced for good” unless it could raise $800,000 in 10 days.

While Castro's rivals lamented his departure from the race, Sen. Cory Booker directly referenced the racial dynamic in a fundraising email Thursday, expressing regret that Castro would become "yet another person of color exiting a field of candidates that began as the most diverse in our nation’s history." He called Castro's unsuccessful bid "a loss for our party and this nominating process."

He also took shots at the multiple billionaires who threw their hats into the ring late and have poured close to $200 million of their personal fortunes into their bids. "Here's the reality," Booker wrote. "It seems like billionaires with bottomless checkbooks have a clearer path to the nomination than talented, experienced, qualified candidates" like Castro.

Both men joined every other Democrat in the race in a letter to the DNC last month calling for the debate thresholds to be lowered to allow for more candidates of color on stage. At that point, Castro had already gotten out in front of the field with a call for reshuffling the primary schedule so that it included more diverse states in the beginning of the calendar.

“Ganaremos un día!” Castro says at the end of the video, which includes the English translation in a subtitle: “One day we’ll win!”