Julian Castro, head of the Department of Housing and Urban Development, is meeting with Hillary Clinton's vice presidential search team on Friday, a Democratic official tells U.S. News.

The meeting is a sign that the 41-year-old Castro, a former three-term mayor of San Antonio, is one of the finalists to be Clinton's running mate as her search nears a conclusion.

If selected, Castro would become the nation's first Latino on a major party's presidential ticket.

The meeting between Castro and Clinton's high command – including campaign chairman John Podesta, longtime adviser Cheryl Mills and Washington attorney James Hamilton – comes one day after Clinton appeared on the campaign trail with Sen. Tim Kaine of Virginia, widely thought to be the front-runner for the Democratic VP slot.

Kaine, who is fluent in Spanish, showcased that skill to the crowd in northern Virginia, highlighting an advantage he holds over other prospects including Castro, a Mexican-American who reportedly used a tutor in past years to help him improve his Spanish.

Clinton has no public schedule Friday or through the weekend in order to conduct the final vetting of potential running mates and narrow her decision.

CNN reported last week that Castro was "no longer thought to be in serious contention," citing several Democrats close to the process. But Castro's allies contend the secretary is at least among the final four contenders, even if he's not the front-runner. The knock against him is that he lacks a broad portfolio of high-level governing experience, including most glaringly on global affairs.

The Clinton campaign did not respond to a request for comment from U.S. News. Other running mate options include Ohio Sen. Sherrod Brown, New Jersey Sen. Cory Booker, Labor Secretary Tom Perez and Agriculture Secretary Tom Vilsack, the former two-term governor of Iowa.

Sen. Elizabeth Warren of Massachusetts, who already has been offered a speaking slot on the first day of the Democratic National Convention, is seen as no longer in serious contention.

While President Barack Obama's administration has refused to allow Cabinet officials to speak at the party's convention, an ally to Castro indicated he would resign his post as HUD secretary on the spot if he was chosen to join the ticket.

Clinton is unlikely to announce her selection formally until the conclusion of the Republican National Convention, which will culminate with the official nomination of Donald Trump in Cleveland on Thursday night.