Though 15 Democrats have already dropped out of the 2020 primary, Castro, the most recent to do so, is one of only two to have formally endorsed another candidate to land the nomination. Rep. Tim Ryan (D-Ohio) endorsed former vice president Joe Biden in November. But Castro’s announcement Monday morning was more than a simple vote of confidence. He starred in a fresh campaign video for Warren centered around his endorsement, and he seems poised to act as a surrogate for the Massachusetts senator heading into primary season.
“There’s one candidate I see who’s unafraid to fight like hell to make sure America’s promise will be there for everyone, who 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,” Castro says in the video before greeting Warren and her dog Bailey. “That’s why I’m proud to endorse Elizabeth Warren for president.”
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
During his run, Castro failed to consistently poll as a top-tier candidate, making a vice presidential nod a more likely outcome than winning the nomination. Warren and Castro are ideologically aligned, and although he served with Biden for three years as President Obama’s Housing and Urban Development secretary, there appears no love lost between the two after a number of memorable debate clashes.
Warren could very well be considering Castro as a potential running mate, but she has some work to do before she’ll be able to choose one. Though her campaign caught fire last fall, she’s currently running in a distant third behind Biden and Bernie Sanders. A CBS News/YouGov poll of Iowa voters released Sunday put her at 16 percent in the crucial caucus state, 7 points behind Biden, Sanders, and Pete Buttigieg, who were all tied at 23 percent. The same poll found that in New Hampshire, the second state to choose a nominee, she is running at 18 percent, good for third behind Sanders (27 percent) and Biden (25).
As with most endorsements, however, it’s unclear how much Castro’s nod to Warren will actually matter for the contest’s end result. Castro brought up important issues in the campaign and helped keep other candidates accountable, but he did not attract a broad national following. He was polling at less than 2 percent nationally when he ended his run, according to a polling average from RealClearPolitics.