(CBS News) In 2004, a little-known state senator made his debut on the national stage, delivering the keynote address at the Democratic National Convention. Four years later, Barack Obama was elected president.
On Tuesday night, San Antonio Mayor Julian Castro will become the first Latino ever tapped to give a keynote address at a Democratic National Convention. He's a relative unknown on the national stage, but then again, so was Barack Obama when he gave his keynote speech back in 2004.
Castro told CBS News he has been working on his speech "for a couple of weeks now, going back and forth."
The pages in the mayor of San Antonio's hand are his ticket to the biggest political stage of his life.
"If somebody had told me when I was in my last year of law school that I would be doing this now, I definitely wouldn't told them that they were crazy," Castro joked.
If he looks young, he is.
At 37, Julian Castro is the youngest mayor of any major U.S. city -- a fact not lost on President Obama when Castro visited the White House three years ago.
"The President walked in, and the subject was I think clean energy and jobs, and he walked in and at some point in the conversation he asked if I was an intern," Castro said. "He asked jokingly. But I know I must have looked younger than everybody else there by at least 15 years. So I guess it was understandable."
In Texas, a reliably Red State, some still criticize his age, and his policies. But what the White House is interested in is his background.Complete coverage: Democratic Convention 2012
A Mexican-American, Castro is well aware his role tonight is to help bring Hispanic voters into the Obama tent.
His mother, Rosie Castro was a Latino activist who ran for City Council herself. She lost. Her old campaign poster hangs on the wall of her son's office as a reminder of how things have changed.
"My grandmother and my mother lived during a time when you would see signs that said: "No Mexicans or dogs allowed." America has made profound and wonderful progress since that time," Castro said.
He's not the family's only standard bearer. He has an identical twin brother, Joaquin.
"It's usually me getting called his name," Joaquin Castro said.
They both went to Stanford, both went to Harvard Law, and both went into politics. Joaquin Castro is leading in the polls in the race for his district's Congressional seat.
"I've always believed that as long as you do a great job in whatever you're doing at the moment that there will be opportunities for you, whatever they are. And I still believe that," Joaquin Castro said.
For his brother that opportunity has arrived, and with the polls showing basically a dead heat, he's got his work cut out. There are a lot of people who feel disillusioned, and Julian Castro has to address those folks.
"The economy is not where everybody wants it to be. But if you compare to where we started, the month where he was inaugurated, losing almost 800,000 jobs. You know, change takes time. But you have clearly seen progress," Castro said.
As for his progress, he had gone through three revisions of his speech. Now all he has to do is deliver it.