Julián Castro, who dropped out of the Democratic presidential race last week, threw his support Monday behind Sen. Elizabeth Warren of Massachusetts.

Castro, who was Housing and Urban Development secretary under President Barack Obama, said in a video that he and Warren "share a vision of America where everyone counts, an America where people — not the wealthy or well-connected — are put first." He also mentioned the "strong women" — his grandmother and mother — who raised him.

"There is one candidate I see who is unafraid to fight like hell to make sure America's promise will be there for everyone," Castro says, as the video shows him arriving at Warren's home and being greeted by her with a hug and by her dog, Bailey.

"You did so many things in this campaign and it continues to matter. It's not just in the past tense. It matters," Warren says as she pours coffee for the two in her kitchen.

"No one is working harder than you are, not only in meeting people but in listening to people," Castro says to Warren. "And also bringing the goods, saying, 'OK, this is what I'm going to do about it.'"

The two planned to be on the campaign trail together Tuesday at a rally in Brooklyn, New York at Kings Theatre. The historic theater first opened as a movie house in 1929 with the film Evangeline that starred Dolores del Río, the groundbreaking actress from Mexico.

Today I'm proud to endorse @ewarren for president.



Elizabeth and I share a vision of America where everyone counts. An America where people⁠—not the wealthy or well-connected⁠—are put first. I'm proud to join her in the fight for big, structural change. pic.twitter.com/xDvMEKqpF3 — Julián Castro (@JulianCastro) January 6, 2020

Long before Monday's endorsement, fans of the two mused on social media about a Warren/Castro or Castro/Warren ticket based on their shared progressive views and policy wonkiness. Castro's announcement stirred up such musing again:

Castro was on Hillary Clinton's running mates short list, but she passed on him for Sen. Tim Kaine, D. Va.

Elizabeth Warren raised $21 million in the last quarter, less than what she raised the previous quarter and less than the other leaders in the polls, Joe Biden, Bernie Sanders and Pete Buttigieg.

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Castro was praised for his policy proposals, his outspokenness on the lack of diversity in the field and for calling out what he saw as the institutional bias in the Democratic nomination process. But he could not raise his low poll numbers, often at 1 percent and 2 percent, except in surveys with large pools of Latinos.

In a recent opinion piece for The New York Times, Republican strategist Liz Mair said Castro would be a big asset to the Democratic nominee, calling him "the deftest communicator among all the 2020 contenders and probably one of the deftest communicators in presidential politics over the last few decades."

Like Warren, Castro has issued detailed policy plans and has been seen as a progressive with an agenda that brought attention to the poor, minority communities and marginalized populations.

Thank you, @JulianCastro! You’ve been a powerful voice for bold, progressive change and I’m honored to have your support. Together, we'll fight to make sure every single family in America has a path to opportunity. https://t.co/uHs7DP4DcU — Elizabeth Warren (@ewarren) January 6, 2020

The endorsement is not a surprise given the mutual admiration and the friendship the two have shared during the campaign. Before the video hug, they were seen exchanging an embrace at the Iowa Steak Fry and have boosted each other's ideas and debate performances.

Warren was an early adopter of an immigration proposal that Castro issued at the start of his campaign. Castro has proposed taking immigration back to a time when crossing the border illegally was a civil, not a criminal, violation.

In a Nov. 10 interview with MSNBC, Castro said he had been impressed with the work Warren has done in the African American and Latino communities.

In a separate MSNBC interview, Warren was asked to say something nice about one of her rivals in the nomination race and she gave a shout out to Castro and his immigration plan.

A Latino boost?

Castro, who was the only Latino in the race, could be a help to Warren in attracting Latino votes.

"Elizabeth Warren is an unconventional candidate, but as a white woman, it's very likely she'll pick a man of color to be her No. 2," said Oscar Ramirez, a Democratic political strategist who was an early Castro endorser. "He's been tested on the the campaign side, but also has experience on the executive level that could help with governance."

Less than 6.3 percent of Warren's contributions, a total of $1.2 million, are from Latinos, according to a Plus Three analysis of candidate campaign finance filings. For Castro, 38.7 percent of his contributions were from Latinos, a total of $973,000.

Sanders has raised the most, with $4.72 million coming from Latinos, though they make up 16.2 percent of his contributions, less than Castro's share, Plus Three's analysis found.

Ramirez said Warren has scored a big endorsement in a tight, competitive race among the top-tier candidates.

Castro will be a big help with mobilizing Latino voters in Nevada, which has its caucuses Feb. 22, and California and Texas, which hold primaries on Super Tuesday, March 3, and in Florida, March 17. This is the first year that Latinos will be the largest nonwhite electoral group, at 32 million eligible to vote.

Nelini Stamp, Working Families Party director of strategy and partnerships, called Castro's endorsement a "major shot in the arm" that "put the kind of multiracial coalition Democrats need to win this November front and center."

But Warren will need to step up her inclusion and outreach to Hispanics, said Ramirez, who worked on Obama's 2008 campaign and in the Obama administration.

"For Warren, having someone like Castro endorse her is a first step, but there's a lot she needs to do, including a lot of hiring of Latinos in every part of her campaign, that helps frame and shape the position she takes on politics and policy and communications, not just in terms of who she has internally, including at senior levels in her campaign, but also the vendors and contractors she hires," Ramirez said.

Warren and Castro have not been in sync on a key issue for Castro. He has said it is unfair to voters of color that Iowa and New Hampshire, two states that are more than 90 percent white, are first to vote in the nominating process. But when asked about that view in a South Carolina town hall, Warren deflected saying: "“Look, I’m just a player in the game on this one. And I am delighted to be in South Carolina. Thank you.”

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