Julian Castro: Romney "has no idea how good he's had it"

(CBS News) CHARLOTTE, N.C. -- San Antonio mayor Julian Castro, who was plucked from relative obscurity to give the keynote address at the Democratic National Convention, on Tuesday assailed Mitt Romney as a son of privilege who does not understand that many Americans can't rely on their families to help them succeed.

"Mitt Romney, quite simply, doesn't get it," said the 37-year-old Castro. "A few months ago he visited a university in Ohio and gave the students there a little entrepreneurial advice. 'Start a business,' he said. But how? 'Borrow money if you have to from your parents,' he told them. Gee, why didn't I think of that?"

Castro, who recieved a rapturous reception from the convention crowd, opened his remarks by discussing his grandmother, an orphan who moved from Mexico to San Antonio as a child and ended up with a fourth-grade education. Castro said she worked hard as a maid and in other jobs to give his mother a better life, so that she could then give he and his twin brother an even better one.

"My family's story isn't special. What's special is the America that makes our story possible," said Castro, who was introduced by his identical twin brother, Texas State Rep. Joaquin Castro, who is now seeking a seat in Congress. The two men smiled and waved together on stage before Julian Castro's remarks.

Julian Castro's case against Romney was grounded in the notion that Romney is "perfectly comfortable" with an American in which "some folks won't even get a chance."

"In fact, that's exactly what they're promising us," he said, arguing that the Romney-Ryan budget "dismantles" the middle class by cutting public education funding, Medicare, transportation funding and job training. He also mocked Romney as a flip-flopper who underwent an "extreme makeover."

"We all understand that freedom isn't free," he said. "What Romney and Ryan don't understand is that neither is opportunity. We have to invest in it."

In the last third of his speech, Castro pivoted to an argument for President Obama, saying that the president "understands that when we invest in people we're investing in our shared prosperity. And when we neglect that responsibility, we risk our promise as a nation."

Castro, the first-ever Hispanic keynote convention speaker, was tapped in part to appeal to the crucial and growing Latino voter base that largely supports Mr. Obama but has been disappointed at his failure to deliver on issues like immigration reform. He called on Congress to pass the Obama-backed DREAM Act creating a path to citizenship for certain undocumented immigrants brought to the United States as children.

Near the end of his remarks, Castro described the American dream as "not a sprint, or even a marathon, but a relay."

"Our families don't always cross the finish line in the span of one generation," he said. "But each generation passes on to the next the fruits of their labor. My grandmother never owned a house. She cleaned other people's houses so she could afford to rent her own. But she saw her daughter become the first in her family to graduate from college. And my mother fought hard for civil rights so that instead of a mop, I could hold this microphone."