The number of eligible Hispanic voters is up 4.2 million since 2008, making up 11 percent of the nation's 215 million eligible voters this year, up from 9.5 percent in 2008 and 8.2 percent in 2004, the Pew Hispanic Center analysis of U.S. Census data indicates.
But historically only 50 percent Hispanic voters turn out, a project of Washington's Pew Research Center think tank.
Still if only 12 million Latinos vote Nov. 6, it would be a record for the nation's largest minority group.
Fifty percent of eligible Latinos voted in the 2008, compared with 65 percent of blacks and 66 percent of whites, a 2009 Pew study found.
Some polls indicate more than 60 percent of Latinos could vote for Obama again Nov. 6.
Yet, despite ongoing Latino population growth to 52 million, or 17 percent of the U.S. population, the number of Latinos who said they registered to vote between 2008 and 2010 fell by some 600,000, census data indicated.
This was the first significant decline in the number of Latino registered voters in two decades, Pew said.
National information about Latino voter registration this year is not yet available.
Part of the reason for a relatively low Latino voter turnout is that Hispanics are proportionally younger than other groups -- about a third of are 18 to 29 -- and younger people tend to vote at much lower rates than older people, Pew said.
Blacks, by contrast, are older and vote at higher rates than Latinos in part because their churches often urge them to register and get to the polls, analysts cited by the Los Angeles Times said.
In addition, voting "is not seen as a real need" among many Latinos, who tend to feel disconnected from the broader society, political author Maria Elena Ferrer, a principal of the non-partisan Humanamente consulting firm near New York City, told KSNV-TV, Las Vegas.
"You are not feeling that you count, so maybe you will be thinking why I have to vote if it doesn't count," she said.