San Antonio, Texas Mayor Julian Cast

People on the campaign trail simply call him Julian. For the past month, Julian Castro has been living on a political high with the windfall that electoral currency can give a smart, attractive young candidate who has been anointed The Rising Star.

In that time, Julian Castro has come a long way, psychologically as well as politically, from his home in San Antonio where he is the mayor—a title that doesn’t seem as important right now as what he’s become: He campaigns at the right hand of President Barack Obama’s re-election campaign.

And on Obama’s most recent fundraising swing into California, Castro got the royal Hollywood treatment, meeting the movie stars, show business honchos and billionaires who for years have been the source of hundreds of millions of dollars to national Democratic candidates.

George Clooney wrapped an arm around Julian’s shoulders and whispered something funny into his ear. Katy Perry shook his hand longer than most on the campaign trail—was the 37-year-old political wunderkind her “Teenage Dream”? DreamWorks Animation head Jeffrey Katzenberg told him he was sure they would be seeing each other more in coming years.

Castro all but stole the show at a fundraising concert in front of 6,000 Obama supporters like a teary-eyed Maria Sipin of L.A.’s San Gabriel Valley who said “my hands hurt from clapping” during the Texan’s speech.

“You’ll be the first Hispanic governor of Texas,” another admirer said to him as he was led off the Nokia Theater stage.

Julian Castro, Mayor of San Antonio, TX , and NBC talk show host Jimmy Fallon. (Photos AP/Youtube)

Others asked Castro if he had seen Jimmy Fallon’s impersonation of him on “Late Night”—Julian had—and remarking how they thought the talk show host looked like his identical twin brother.

“Really? I thought he looked more like Joaquin,” said a laughing Castro, referring to his real twin brother, a Texas legislator who is running for Congress.

Through it all, Castro took in all the lavish admiration and compliments with a humility that those who know him say is genuine and true to his modest roots.

Julian Castro: ‘Something has to change in Texas‘

But Julian Castro is also extremely smart—brilliant, in fact—and the humble manner in which he carries himself in the political stratosphere in which’s he’s found himself is also due to knowing the reality of Texas politics.

Of the 29 statewide offices in Texas, not a single post is held by a Democrat. That is how solid of a Red State the home of Lyndon Johnson has become in the past generation. Democrats are hoping that the growing Latino population—currently 38 percent and estimated to reach above 50 percent in the 2030s, possibly sooner.

That would seem ideal for a Democratic takeover until one understands another sobering reality.

Today, more than half of the state’s population under 18 is Latino and ineligible to go to the polls. By 2015, almost a third of all Hispanics in Texas will still be too young to vote.

“For me, or for any Democrat,” says Castro, “something has to change in the state before a Democrat is going to get elected.”

Still, that has not kept Julian Castro from becoming the most sought-after Obama surrogate, Latino or otherwise, surpassing in popularity Los Angeles Mayor Antonio Villaraigosa.

That itself became a source of small embarrassment last week when the Obama campaign rolled into tiny Keene, Calif., where the president dedicated a historical monument to Cesar Chavez, the late farm labor leader and Latino patron figure.

Villaraigosa was among the Hispanic politicians who accompanied Obama, but many in the crowd wanted to see Castro, with a few in the crowd even vocal about it.

“Where’s Julian?” they wanted to know.

Castro had a prior commitment in Chicago where he joined that city’s mayor, Rahm Emanuel—Obama’s former chief of staff—to announce a joint campaign between their two cities to improve healthy lifestyle choices among their residents.

It has been enough to whet the political appetites of Democrats outside his beloved home who would like to see him in higher office, possibly on a national stage.

“I’m not interested in that,” says Castro in a manner that is neither convincing nor dismissive. “It’s not what I want to do.”

“Afterwards, as my tenure in San Antonio comes to a close, if I were to look at another position, it would be in Texas.”