As the general election for president has come into focus, there has been no doubt whom the Castro brothers will support.

Julián Castro, the former U.S. housing secretary and mayor of San Antonio, reiterated that again this week.

“Everybody understands that the No. 1 goal has to be to replace this president,” he told “The New Abnormal” podcast Tuesday. “That is certainly my goal to replace the president, and I’m going to do whatever I can, whatever is asked, to do that.”

But with Democrats all but unified behind former Vice President Joe Biden as their presidential nominee, two of the party’s highest-profile members in Texas have not made their support official yet. Neither Julián Castro nor his brother, U.S. Rep. Joaquin Castro, has formally endorsed Biden, though both insist they are committed to ensuring the defeat of President Donald Trump in November.

It may seem like a trivial distinction at this point in the election cycle, but their level of outward support has lagged behind that of other prominent Texas Democrats who have issued statements and campaign videos explicitly endorsing Biden, including almost every member of the congressional delegation. Their level of outward support also pales in comparison to the enthusiastic endorsement and support they gave a former Biden rival, Elizabeth Warren, and it comes as questions are being raised about the Biden campaign’s Latino outreach.

The Castro twins could potentially be important surrogates for the presumptive Democratic nominee if Biden’s campaign chooses to seriously compete against Trump in the historically red state. Biden has said he plans to take the Lone Star State seriously, along with recently Republican-dominated states like Georgia and Arizona. But while it’s early and the coronavirus has disrupted the campaign, what role, if any, the Castros would have in such a push has not been made clear.

Julián Castro, who ran against Biden in the primary until calling it quits at the start of the year, urged Democratic unity behind Biden once U.S. Sen. Bernie Sanders dropped out of the race in early April. Yet in addition to withholding a formal endorsement so far, Julián Castro has not spoken with Biden since the former ended his own campaign nearly five months ago. That was first reported earlier this month by Politico.

A Julián Castro spokesperson declined to comment for this story other than to emphasize that he is focused on doing everything he can to beat Trump. The spokesperson also pointed to Castro’s tweet April 8 — the day Sanders dropped out — saying Democrats “must now come together behind [Biden] to defeat Donald Trump and restore integrity, decency, and competence to the Oval Office.”

It appears the lack of a formal endorsement by Julián Castro may be more due to campaign logistics than any reservations on his part. A source close to him said after this story was initially published that his team has reached out to the Biden campaign to formalize an endorsement, but nothing had been scheduled yet.

As for Joaquin Castro, the San Antonio representative, his formal endorsement would carry additional weight because he chairs the Congressional Hispanic Caucus. The caucus’ political arm endorsed Biden in March, a few weeks after he swept the Super Tuesday primary states — including Texas — and began his march to the nomination.

“Joaquin has said all along that he would do everything he can to support the Democratic nominee for President and he has made it clear — to use the Vice President’s own words — that he’s going to do everything he can to make sure Joe Biden beats Trump like a drum,” Joaquin Castro spokesman Matt Jones said in a statement.

The Biden campaign had no comment for this story.

The Castros are not the only prominent Texas Democrats who have not formally endorsed Biden. Two members of the congressional delegation — Reps. Lloyd Doggett of Austin and Al Green of Houston — also have not, though Doggett’s team made clear in a statement for this story that he supports Biden.

The Castros had a somewhat complicated relationship with Biden during the primary.

Julián Castro and Biden had a rough patch when the former sharply questioned Biden’s memory at a September debate while they were arguing over health care. But Biden did not seem to hold a grudge, heaping praise on Julián Castro during a fundraiser a few months later in San Antonio, for example. Still, the two have not publicly embraced in the way that other past Democratic primary rivals have.

Julián Castro endorsed Warren for president four days after he dropped out of the presidential race. The next day, the brothers appeared at an event with her in New York. Julián Castro, explaining his support for the Massachusetts senator, described her as a “fighter for everyday Americans.” Nearly a week later, Joaquin Castro formally endorsed Warren for president, too.

Over the course of her campaign, which ended in mid-March, both brothers became high-profile surrogates for Warren. Julián Castro, who appeared in a flurry of campaign events for Warren across the country, for example, hosted a town hall for Warren in his San Antonio hometown in late February. He also stumped for her in Nevada, Iowa, New Hampshire and Colorado. The weekend before the March 3 primary, he hosted several get-out-the-vote canvass events across Texas for her.

But while Warren endorsed Biden in April and is now receiving considerable buzz as a potential running mate, the Castros have stayed low-key in their support. Their relative silence so far has stood out among the once-crowded field of other Democratic candidates, including fellow Texan Beto O’Rourke, who have been visible backers of Biden.

The day before Super Tuesday, onetime rivals Amy Klobuchar and Pete Buttigieg endorsed Biden at campaign events in Dallas. O’Rourke, who dropped out of the presidential race last fall, also endorsed Biden and has since headlined a virtual campaign event for him, telling supporters they could guarantee a decisive defeat of Trump by delivering Texas for the presumptive nominee.

Even Sanders, who had a notoriously acrimonious relationship with Hillary Clinton during the 2016 presidential race, announced an alliance with Biden in April, pledging to do everything he could do defeat Trump, whom Sanders has called “the most dangerous president” in modern times.

Julián Castro has remained visible in recent weeks, participating in a host of virtual events related to state and national politics. On Thursday, he launched People First Future, a new political action committee committed to investing in progressive candidates across the country. In addition, he was recently named a senior adviser to Voto Latino, focused on helping the national group register and turn out Latino voters for the November election.

On “The New Abnormal” podcast, he also defended Biden after the former vice president told a radio host that black voters torn between voting for him and Trump “ain’t black,” remarks that sparked a firestorm online. Biden later apologized.

“It was really nice to see an adult who can acknowledge when he said something in a way, perhaps, he didn’t mean,” Julián Castro said. “He was very good to say right away, ‘Hey look, I’ve never taken the black community for granted.’”

He also said on the podcast he wasn’t banking on position in a potential Biden administration.

“For the first time in a long time, I’m actually looking at a longer runway outside of politics,” he said. “I can’t say definitively that I wouldn’t. If it’s something that I am interested in and it is something that the Biden administration is interested in for me, of course I would consider that.”

Last week, Julián Castro and Warren reunited for their first appearance together since the end of her campaign, a virtual event organized by the immigrant youth group United We Dream. During the discussion, Warren said she could not have asked for a “better partner in a moral fight” than him. Castro will also hold an Instagram Live event with Warren on Thursday afternoon to discuss the launch of his newest PAC.

As for Green and Doggett, Green previously supported Kamala Harris in the primary. He has stayed silent since her candidacy ended, however, although Harris is being floated as a potential Biden running mate.

A spokesperson for Doggett, meanwhile, said that while the representative chose not to endorse before his own contested primary, he “supports Joe Biden, whose victory is essential to saving our democracy from a wannabe tyrant.” Doggett’s spokesperson added that he’s expressed his support for Biden before, albeit more privately, to “some Democratic groups.”

This article originally appeared in The Texas Tribune, a nonpartisan, nonprofit media organization that informs Texans – and engages with them – about public policy, politics, government, and statewide issues.

Patrick Svitek and Alex Samuels, The Texas Tribune

Patrick Svitek is the primary political correspondent for The Texas Tribune. Alex Samuels is a political reporter for The Texas Tribune.