CHARLOTTE, N.C. — When San Antonio Mayor Julian Castro walked onto the stage Tuesday night and shared the story of his grandmother coming from Mexico to build a life in the United States, Democrats were counting on him to energize the party’s base and electrify Latino voters who could be decisive in the November election.

Latinos took center stage on opening night of the Democratic National Convention. Not only was Castro the first Latino to give the keynote address, but he was speaking to the highest number of Latino delegates, around 800, at any presidential convention.

“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,” Castro said in remarks prepared for his speech before nearly 6,000 energized delegates and alternates.

Latino voters are being wooed by both Democrats and Republicans to a degree never before seen.

The fastest-growing voter bloc could be the difference in November, as the election will likely be decided in battleground states – such as Florida and Colorado – with large Hispanic populations. And Latino delegates in North Carolina are reminding supporters that Barack Obama won the state by a mere 14,000 votes. Exit polls showed Obama received 26,000 more Latino votes than McCain, according to the Immigration Policy Institute.

Latinos make up just a fraction of North Carolina’s 6.4 million registered voters, but their voter registration numbers have doubled in the past four years. Arturo Vargas, executive director of the National Association of Latino Elected and Appointed Officials, said Latinos could decide the state if they vote in a bloc.

“Everyone wants to be asked to the dance,” he said. “The key here is that there will be no majority party in this country without participation from Latinos. We’re already 16 percent of the population, 9 percent of the voters. It’s only going to increase.”

At a Hispanic Caucus meeting this week, N.C. delegate Matty Lazo-Chadderton, who lives in Cary, called on South Carolina Latino delegates to come to Charlotte to help mobilize Latinos in the state.

“We’re fired up,” said Lazo-Chadderton, who is originally from Peru.

“We’re walking the walk. The Hispanic vote is more important than people realize.”

In his prepared speech Tuesday, Castro stuck to President Obama’s campaign script focusing on the middle class, a message that should resonate with Latino voters.

He spoke about the importance of Pell Grants for education and keeping jobs in America. And he criticized Romney for failing to understand the challenges most Americans face.

“Republicans tell us that if the most prosperous among us do even better, that somehow the rest of us will too,” he said. “Folks ... we’ve heard that before.”

Democrats need Castro’s help erasing a 4-point bump GOP candidate Mitt Romney received after trotting out a list of prominent Latino Republican elected officials, including superstar U.S. Sen. Marco Rubio, R-Fla., at the Republican National Convention last week in Tampa.

Romney support is now 30 percent among Latinos polled, up from 26 percent the week before, according to a new impreMedia/Latino Decisions poll released Monday.

President Obama continues to enjoy more than 60 percent support from Latinos, but Vargas said it’s a misconception to believe that Latinos will automatically line up behind any candidate. Many experts point out that Sen. John McCain received only 31 percent of the Latino vote in 2008, according to some exit polls, as an example of Republicans’ diminishing sway among Latinos. But Vargas notes that George W. Bush garnered 44 percent of the Hispanic vote in 2004.

The Republican stance against illegal immigration has alienated many Latinos from the Republican party. Romney has advocated for “self deportation” and criticized Obama for granting hundreds of thousands of young illegal immigrants a reprieve from deportation.

But leading Republicans have been pushing from inside for a more moderate stance. Rubio introduced a similar proposal for young immigrants this year. And former Florida Gov. Jeb Bush has advocated against the hard-line approach and said the GOP could to appeal to Latinos “if we just stop acting stupid.”

Latino’s historically strong Catholic and Christian beliefs fit well with Republican ideals. Many oppose Democratic stands on issues such as gay marriage and abortion rights.

Latinos are the “ultimate swing voters,” said Janet Murguia, president of the National Council of La Raza.

Voter turnout among Latinos is key for both parties as they enter the critical last two months of the campaign, said Monica Lozano, CEO of impreMedia, a Hispanic news company. Latinos for Obama and Juntos con Romney have very well-developed strategies. They’re using televisions and radio advertising, social media and online town halls aimed at influencing this constituency.

“Every tool has now been fully deployed,” Lozano said. “… This is without a doubt the most sophisticated and comprehensive effort to reach Hispanic voters in our political history.”