Julian Castro Prepares for DNC Spotlight

Little-known San Antonio mayor to give Tuesday keynote address

They were both young, relatively unknown politicians from a key demographic chosen to give a keynote speech at one of the nation's biggest stages — the Democratic National Convention — and expected to wow the crowd.

But the similarities between then-Illinois state Sen. Barack Obama, who gave the keynote address at the DNC in 2004, and San Antonio Mayor Julian Castro, Tuesday night's keynote speaker, end there.

Castro, 37, is by all accounts a relatively shy and humble mayor devoted to his young family and tight with his twin brother, a congressional candidate who will introduce him at the convention. (Friends say its nearly impossible to tell them apart). He's never played a big role on the national political scene and would probably be embarrassed by headlines calling him the Democrats' "messiah" and a potential first Latino president of the United States.