By BETH FOUHY AND PAUL J. WEBER, ASSOCIATED PRESS

CHARLOTTE, N.C. — San Antonio Mayor Julian Castro's keynote speech to the Democratic convention was a spicy blend of immigrant dreams and partisan bite.

The 37-year old Castro, a rising star in Texas but little known on the national stage, roused the packed audience at the Time Warner Center with a pointed message to voters: "Mitt Romney, quite simply, doesn't get it."

Castro's tale was in part standard political fare for a party seeking to solidify its standing among immigrant voters.

Castro was raised by a single mother and a grandmother who both emigrated from Mexico, Castro and his identical twin brother Joaquin achieved happiness and success through hard work and a good education made possible by the American dream. But from there, Castro pivoted to an assault on Republican Mitt Romney, whose policies Castro said would "dismantle" the middle class if elected.

"We know that in our free market economy some will prosper more than others. What we don't accept is the idea that some folks won't even get a chance," Castro said. "And the thing is, Mitt Romney and the Republican party are perfectly comfortable with that America."

He added, "I don't think Gov. Romney meant any harm. I think he's a good guy. He just has no idea how good he's had it," – a pointed jab at Romney's considerable wealth.

Castro also taunted Romney for his shifting positions on issues like abortion rights, gay marriage and his own push for universal health care as governor of Massachusetts.

"Gov. Romney has undergone an extreme makeover, and it isn't pretty," Castro said.

The Romney campaign shot back at Castro's claim the GOP presidential nominee is insensitive to the middle class.

"Middle class families understand that they are not better off than they were four years ago because President Obama's liberal policies have failed to turn around the economy," spokesman Ryan Williams said.

Until now, Castro has enjoyed a spate of favorable media profiles, a landslide re-election last year and speculation about whether he'll become the governor of Texas or even the country's first Hispanic president. His well-received turn at the convention all but guarantees more of such chatter.

Castro was introduced onstage his brother Joaquin, a Texas state legislator from San Antonio now poised to win election to Congress in November

"My family's story isn't special. What's special is the America that makes our story possible," Julian Castro said. "Ours is a nation like no other, a place where great journeys can be made in a single generation. No matter who you are or where you come from, the path is always forward."

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  • President Barack Obama waves with his wife Michelle and his daughters Malia and Sasha after his speech to the Democratic National Convention in Charlotte, N.C., on Thursday, Sept. 6, 2012. (AP Photo/Lynne Sladky)

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    Vice President Joe Biden and President Barack Obama wave to the delegates at the conclusion of Presdident Obama's speech at the Democratic National Convention in Charlotte, N.C., on Thursday, Sept. 6, 2012. (AP Photo/J. Scott Applewhite)

  • President Barack Obama waves with his wife Michelle and his daughters Malia and Sasha after his speech to the Democratic National Convention in Charlotte, N.C., on Thursday, Sept. 6, 2012. (AP Photo/Lynne Sladky)

  • President Barack Obama waves with his wife Michelle and his daughters Malia and Sasha after his speech to the Democratic National Convention in Charlotte, N.C., on Thursday, Sept. 6, 2012. (AP Photo/Lynne Sladky)

  • President Barack Obama waves with his wife Michelle and his daughters Malia and Sasha after his speech to the Democratic National Convention in Charlotte, N.C., on Thursday, Sept. 6, 2012. (AP Photo/Lynne Sladky)

  • President Barack Obama waves with his wife Michelle and his daughters Malia and Sasha after his speech to the Democratic National Convention in Charlotte, N.C., on Thursday, Sept. 6, 2012. (AP Photo/Charlie Neibergall)

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  • Obama Accepts Nomination On Final Day Of Democratic National Convention

    CHARLOTTE, NC - SEPTEMBER 06: Democratic presidential candidate, U.S. President Barack Obama speaks on stage as he accepts the nomination for president during the final day of the Democratic National Convention at Time Warner Cable Arena on September 6, 2012 in Charlotte, North Carolina. The DNC, which concludes today, nominated U.S. President Barack Obama as the Democratic presidential candidate. (Photo by Win McNamee/Getty Images)

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    CHARLOTTE, NC - SEPTEMBER 06: Democratic presidential candidate, U.S. President Barack Obama speaks on stage as he accepts the nomination for president during the final day of the Democratic National Convention at Time Warner Cable Arena on September 6, 2012 in Charlotte, North Carolina. The DNC, which concludes today, nominated U.S. President Barack Obama as the Democratic presidential candidate. (Photo by Streeter Lecka/Getty Images)

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  • From left, Michelle Obama's mother Marian, Malia and Sasha Obama, their mother Michelle and Dr. Jill Biden, wife of Vice President Biden, listen to President Barack Obama at the Democratic National Convention in Charlotte, N.C., on Thursday, Sept. 6, 2012. (AP Photo/Lynne Sladky)

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    CHARLOTTE, NC - SEPTEMBER 06: Democratic presidential candidate, U.S. President Barack Obama claps on stage as he accepts the nomination for president during the final day of the Democratic National Convention at Time Warner Cable Arena on September 6, 2012 in Charlotte, North Carolina. The DNC, which concludes today, nominated U.S. President Barack Obama as the Democratic presidential candidate. (Photo by Win McNamee/Getty Images)

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    CHARLOTTE, NC - SEPTEMBER 06: Democratic presidential candidate, U.S. President Barack Obama speaks on stage to accept the nomination for president during the final day of the Democratic National Convention at Time Warner Cable Arena on September 6, 2012 in Charlotte, North Carolina. The DNC, which concludes today, nominated U.S. President Barack Obama as the Democratic presidential candidate. (Photo by Chip Somodevilla/Getty Images)

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    CHARLOTTE, NC - SEPTEMBER 06: Democratic presidential candidate, U.S. President Barack Obama speaks on stage as he accepts the nomination for president during the final day of the Democratic National Convention at Time Warner Cable Arena on September 6, 2012 in Charlotte, North Carolina. The DNC, which concludes today, nominated U.S. President Barack Obama as the Democratic presidential candidate. (Photo by Kevork Djansezian/Getty Images)

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    CHARLOTTE, NC - SEPTEMBER 06: Democratic presidential candidate, U.S. President Barack Obama speaks on stage as he accepts the nomination for president during the final day of the Democratic National Convention at Time Warner Cable Arena on September 6, 2012 in Charlotte, North Carolina. The DNC, which concludes today, nominated U.S. President Barack Obama as the Democratic presidential candidate. (Photo by Joe Raedle/Getty Images)

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    CHARLOTTE, NC - SEPTEMBER 06: Democratic presidential candidate, U.S. President Barack Obama hugs his wife First lady Michelle Obama during the final day of the Democratic National Convention at Time Warner Cable Arena on September 6, 2012 in Charlotte, North Carolina. The DNC, which concludes today, nominated U.S. President Barack Obama as the Democratic presidential candidate. (Photo by Alex Wong/Getty Images)

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    CHARLOTTE, NC - SEPTEMBER 06: Democratic presidential candidate, U.S. President Barack Obama waves on stage during the final day of the Democratic National Convention at Time Warner Cable Arena on September 6, 2012 in Charlotte, North Carolina. The DNC, which concludes today, nominated U.S. President Barack Obama as the Democratic presidential candidate. (Photo by Justin Sullivan/Getty Images)

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    CHARLOTTE, NC - SEPTEMBER 06: Democratic presidential candidate, U.S. President Barack Obama walks on stage to join First lady Michelle Obama during the final day of the Democratic National Convention at Time Warner Cable Arena on September 6, 2012 in Charlotte, North Carolina. The DNC, which concludes today, nominated U.S. President Barack Obama as the Democratic presidential candidate. (Photo by Streeter Lecka/Getty Images)

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    CHARLOTTE, NC - SEPTEMBER 06: Democratic presidential candidate, U.S. President Barack Obama walks on stage to join First lady Michelle Obama during the final day of the Democratic National Convention at Time Warner Cable Arena on September 6, 2012 in Charlotte, North Carolina. The DNC, which concludes today, nominated U.S. President Barack Obama as the Democratic presidential candidate. (Photo by Streeter Lecka/Getty Images)

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    CHARLOTTE, NC - SEPTEMBER 06: Democratic presidential candidate, U.S. President Barack Obama walks on stage during the final day of the Democratic National Convention at Time Warner Cable Arena on September 6, 2012 in Charlotte, North Carolina. The DNC, which concludes today, nominated U.S. President Barack Obama as the Democratic presidential candidate. (Photo by Justin Sullivan/Getty Images)

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    CHARLOTTE, NC - SEPTEMBER 06: Democratic vice presidential candidate, U.S. Vice President Joe Biden waves with his wife Second lady Dr. Jill Biden after speaking on stage during the final day of the Democratic National Convention at Time Warner Cable Arena on September 6, 2012 in Charlotte, North Carolina. The DNC, which concludes today, nominated U.S. President Barack Obama as the Democratic presidential candidate. (Photo by Chip Somodevilla/Getty Images)

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    CHARLOTTE, NC - SEPTEMBER 06: Democratic vice presidential candidate, U.S. Vice President Joe Biden hugs his wife Second lady Dr. Jill Biden after speaking during the final day of the Democratic National Convention at Time Warner Cable Arena on September 6, 2012 in Charlotte, North Carolina. The DNC, which concludes today, nominated U.S. President Barack Obama as the Democratic presidential candidate. (Photo by Chip Somodevilla/Getty Images)

  • Obama Accepts Nomination On Final Day Of Democratic National Convention

    CHARLOTTE, NC - SEPTEMBER 06: Democratic vice presidential candidate, U.S. Vice President Joe Biden speaks on stage during the final day of the Democratic National Convention at Time Warner Cable Arena on September 6, 2012 in Charlotte, North Carolina. The DNC, which concludes today, nominated U.S. President Barack Obama as the Democratic presidential candidate. (Photo by Alex Wong/Getty Images)

  • Obama Accepts Nomination On Final Day Of Democratic National Convention

    CHARLOTTE, NC - SEPTEMBER 06: Democratic vice presidential candidate, U.S. Vice President Joe Biden speaks on stage during the final day of the Democratic National Convention at Time Warner Cable Arena on September 6, 2012 in Charlotte, North Carolina. The DNC, which concludes today, nominated U.S. President Barack Obama as the Democratic presidential candidate. (Photo by Alex Wong/Getty Images)

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