Businessweek has an article with an argument I've heard before and don't really buy, namely that Latinos in the United States will turn out in part because of Obama's visits to Latin America.
“The president desperately needs high voter turnout among Hispanic Americans,” said Douglas Brinkley, a presidential historian at Rice University in Houston. “It doesn’t hurt for him to be in Colombia, and being seen with Latino leaders of the hemisphere is not a bad photo-op in an election year.”
Obama’s campaign is gearing up for a close election fight against Republican Mitt Romney, putting a premium on gaining an edge with any voting group. Obama is actively courting Hispanics -- who gave him 67 percent of their votes in 2008 -- with a Spanish-language website and by recruiting Spanish-speaking volunteers and using Spanish-language voter registration forms and phone banks.
“Key swing states that have large Hispanic populations will be extremely attentive” to the trip, said Susan MacManus, professor of political science at the University of South Florida in Tampa. “Many feel that Latin and South America has been ignored.”
I just don't see evidence for this. Check out this December 2011 poll from the Pew Hispanic Center on the most important issues for Latinos:
Latinos are concerned about their lives here, not policy toward their country of origin (Cuba excepted, of course). I can't figure how a visit to Colombia will suddenly prompt a Colombian-American to vote when they otherwise wouldn't have, or vote for Obama when they were thinking of Romney. Or at least there will be so few as to be inconsequential.
Update: The Miami Herald has the same argument. But where's the empirical evidence?