Shortly after ending his own presidential campaign, Julian Castro announced his endorsement for Senator Elizabeth Warren. The former housing secretary made the announcement in a Monday Twitter post, saying Warren has a vision where everyone counts.

"An America where people⁠— not the wealthy or well-connected⁠— are put first," he tweeted. "I'm proud to join her in the fight for big, structural change."

Castro's tweet included a video statement, saying Warren "is one candidate I see who’s unafraid to fight like hell to make sure America’s promise will be there for everyone.”

Warren replied to the endorsement with her own statement on Twitter. 

"You’ve been a powerful voice for bold, progressive change and I’m honored to have your support," she said. "Together, we'll fight to make sure every single family in America has a path to opportunity."

According to The New York Times, Castro plans to join Warren on Tuesday at a rally at Kings Theatre in Brooklyn.

“You know, I started my campaign off, and we lived true to the idea that we want an America where everyone counts,” Castro said in the video. “It’s the same vision that I see in you, in your campaign, in the America that you would help bring about.”

The former mayor of San Antonio was the only Latinx candidate in the presidential race, focusing on immigration issues and encouraging more diversity in politics. According to CNN, Castro expressed concerns about the primary system which allows voters in states such as Iowa and New Hampshire to vote first, saying those states don't value diversity.

Warren and Castro's political values were well aligned during their presidential campaigns, CNN reported. At the same time, Castro was critical of his other former opponents. 

During the September's Democratic debate, the 45-year-old took a shot at presidential contender and former U.S. Vice President Joe Biden while discussing health care. 

"You require them to opt-in and I wouldn't require them to opt-in," Castro said to Biden. "They would automatically be enrolled. They wouldn't have to buy in."

When Biden defended himself, saying he wouldn't require people to opt-in, Castro challenged the former vice president's memory.

"You just said two minutes ago that they would have to buy in," Castro said. "Are you forgetting what you said two minutes ago?"

According to Vox, the former presidential candidate has been rumored to be a possible choice for vice president if Warren wins the nomination.

In his statement Monday, Castro said Warren "will make sure that no matter where you live in America or where your family came from in the world, you have a path to opportunity too. That's why I'm proud to endorse Elizabeth Warren for president."

Castro and Warren reportedly discussed the endorsement after he ended his campaign last week. The former housing secretary then went to Boston to record the endorsement video.

Warren currently stands third in the polls, behind Biden and Bernie Sanders, The New York Times reported.

2020-Democratic-Primary2020-Presidential-ElectionJulián CastroSen. Elizabeth Warren