CHARLOTTE, N.C. – San Antonio Mayor Julian Castro delivered his keynote address to the Democratic National Convention tonight and broke through on the national stage in a way not seen among Texas Democrats since the days of Ann Richards and Barbara Jordan.

It was a speech that discussed his family’s immigration story and the broader Democratic Party’s themes of social and economic justice.

“The American dream is not a sprint, or even a marathon, but a relay,” he said. “Our families don’t always cross the finish line in the span of one generation. But each generation passes on to the next the fruits of their labor.”

But unlike New Jersey Gov. Chris Christie’s keynote address at the Republican convention one week ago, Castro mentioned his party’s presidential nominee, President Barack Obama, in almost his first breath.

He did take a while to mention Republican nominee Mitt Romney, and when he did, it was with a velvet glove.

Nearly halfway through the speech, Castro gave the crowd his first of two variations of “Mitt Romney just doesn’t get it.”

“I don’t think Gov. Romney meant any harm,” Castro added. “I think he’s a good guy. He just has no idea how good he’s had it.”

The 37-year-old mayor’s twin brother, state Rep. Joaquin Castro, introduced him to the national audience, calling him his “best friend.”

Julian Castro incorporated anecdotes about Joaquin, their grandmother, mother and his daughter.

“My family’s story isn’t special,” he said. “What’s special is the America that makes our story possible.”

He also used imagery of his home state of Texas and its identification with “rugged individualism” to drive home his economic points.

“Texas may be the one place where people actually still have bootstraps, and we expect folks to pull themselves up by them,” he said. “But we also recognize that there are some things we can’t do alone. We have to come together and invest in opportunity today for prosperity tomorrow.”

He closed the speech with a refrain he used often in the speech – a Spanish translation of “May God bless you.” It was an expression his grandmother said to the brothers each morning in their childhood.

Castro was a central focus of attention and curiosity in the day leading up to his keynote. But until Mayor Castro was selected as keynote speaker, he and his twin brother had achieved political parity in the Lone Star State.  

“In Texas, it’s not news to us that there’s not just one Castro. There’s two,” Texas Democratic consultant Jeff Rotkoff said.

State Rep. Castro is all but certain to fill retiring Rep. Charlie Gonzalez’s (D) 20th district House seat. Before Gonzalez announced he would not seek re-election, Joaquin was preparing for an epic primary against longtime Texas Democratic Rep. Lloyd Doggett.

Rotkoff was also quick to note a major difference in their image: Julian Castro has served as mayor in a nonpartisan environment. Joaquin Castro, on the other hand, has been in the Texas Legislature during some of the more recent partisan state fights. One brother has built his image as someone able to govern, while the other is an effective political combatant.

“I think that obviously, the mayor has gotten an understandable amount of national attention, as he should as a fantastic mayor and future leader of the state, but I think it is a mistake to limit . that analysis with the mayor and not draw the same conclusions about Joaquin Castro,” Rotkoff said.

Texas Republicans will concede that as the Texas Democratic Party struggles for relevance, either of the Castros are postured to be major political players when Hispanics are expected to heavily influence political demographics.

“In Texas in particular, there are only a handful of people you can look to as leaders in the Democratic Party and the Castros are people who are energizing to the base and are working to rebrand the party,” a Texas Republican consultant said.

“I wouldn’t discount one over the other,” the consultant added.