A record 14.7 million Latino voters sat out the 2010 midterm elections, according to a report by the Pew Hispanic Center that shows the nation’s fastest-growing minorities are largely failing to exercise their right to vote.

Along with Asian voters, who appear similarly disengaged, the absence of so many Latino voters at the polls means the political influence of these minority groups will fall short of their demographic strength by years, if not decades.

About 31 percent of eligible Latino and Asian voters cast ballots in the 2010 congressional elections, compared with 49 percent of eligible white voters and 44 percent of eligible blacks, according to the Pew report. Asians comprise a much smaller portion of the electorate than Latinos, though both groups are exploding in size.

Although the number of Latino voters increased from 5.6 million in the 2006 election to 6.6 million last year, the number of Latinos eligible to vote grew much faster, from 17.3 million to 21.3 million, said Mark Lopez, associate director of the Pew Center and author of the report. As a result, the gap between potential and actual Latino voters grew by 3.1 million in 2010.

The snapshot of minority voting comes on the heels of a poll showing that support for President Obama among Latinos is down by more than 25 percentage points compared with the start of his administration — cause for serious concern among Democrats.

Obama needs Latinos to show up in force for him in 2012, as they did in 2008, political analysts say. But the administration has disappointed many Latinos by failing to win immigration reforms while increasing deportations among the country’s 11 million undocumented immigrants.

“You can’t say during a campaign, ‘A child should not be taken from her mother’s arms’ and ‘Children should not come home to find their parents have been taken away by immigration officials,’ and then conduct one of the most massive deportations of immigrants in the history of the country,” said Rep. Luis V. Gutierrez (D-Ill.), who blamed Obama’s immigration stance for lackluster turnout among Latinos.

The administration is on track to deport more undocumented immigrants than any previous administration — Republican or Democrat — in history.

Obama says that he supports an immigration overhaul and has called on Congress to act. In the meantime, he has said, he is obliged to enforce the immigration laws on the books.

But Republicans and Democrats are deeply divided, and reform is unlikely in the remaining two years of Obama’s term. The closest that Congress came to addressing the issue was in December, when Democrats failed to win passage of the Dream Act, a measure that would have created a path to citizenship for some immigrants brought to the United States illegally as children.

Recognizing that legislative action was unlikely anytime soon, 22 senators wrote to Obama this month asking him to use his executive powers to stop deportations of undocumented students.

Several Democrats, including Senate Majority Leader Harry M. Reid (Nev.) and Sen. Barbara Boxer (Calif.) were reelected last year with strong Latino support, but on the whole, GOP candidates fared better than expected among Latino voters. That was especially true of Latino GOP candidates.

“During the November 2010 midterm elections, the Republican Party had historic levels of Hispanic support,” said Rep. Lamar Smith (R-Tex.), chairman of the House Judiciary Committee. “In fact, exit polls showed that 38 percent of Hispanic voters cast ballots for House Republican candidates. This is more than in 2008 and 2006. . . . All five Hispanics elected to Congress in 2010 were Republicans.”

Smith said that calls for strong border protection and enforcement had played well in Florida, Mexico and Nevada, including with Latino voters.“This is a good trend for the GOP,” he said.

The Pew report on minority voting, which was released Tuesday, did not examine the political factors that affect turnout, but it says the youthfulness of the Latino electorate might partly explain the phenomenon. Voters younger than 29 typically do not show up to vote as reliably as older voters.

Clarissa Martinez, director of immigration and national campaigns at the National Council of La Raza, a pro-immigration group, said political candidates were not investing enough effort in reaching out to and mobilizing Latino voters. She blamed Democratic candidates for taking Latino voters for granted and blamed Republicans for writing Latinos off.

Martinez credited Obama for articulating an immigration enforcement policy that focuses on undocumented immigrants with criminal backgrounds and prioritizes them for deportation.

“That should be the policy,” she said. “Instead, what we are seeing is that [they] are picking up moms and dishwashers and workers. The policies have been articulated — they need to be adhered to.”