The Republican grip on Cuban-American voters lasted all the way through the beginning of the last decade. Cuban-American voters identified themselves as Republican by a margin of 64 percent to 22 percent, according to a Pew Center survey of Latino Americans in 2002. George Bush won 78 percent of the Cuban vote in Florida in the 2004 presidential election, according to exit polls.

All of that changed over the past 10 years. The 2013 Pew survey showed that the Republican advantage among Cuban-Americans had dwindled to 3 percentage points, 47 to 44. The Florida exit poll in 2012 showed that Mr. Obama won the Cuban-American vote, 49 to 47 percent. Last month, the exit polling showed that Cuban-American voters supported the Democrat Charlie Crist, 50 to 46 percent, though he lost the governor’s race.

Whether Democrats are actually winning the Cuban-American vote is a matter of some debate. The exit poll samples are small and they are subject to error even when they’re large. Heavily Cuban areas of Miami-Dade County, like Hialeah, continue to vote Republican — though Cuban-American voters who choose to live in the most heavily Cuban areas may not be representative of the overall group’s preferences.

But whether Mr. Obama received 49 or 42 percent of the Cuban-American vote is a little beside the point. There is no question that Republicans have suffered huge losses among Cuban-American voters over the last decade.

Some of the Democratic gains result from generational replacement. The Cubans who arrived at the height of the Cold War represent a dwindling share of the population. Cuban-Americans of the new generation, born in the United States, have no memory of that era, and they’re far more likely to identify as Democrats than older Cubans, according to the Pew data. The exit poll in 2012 showed the same thing: Mr. Obama won Cuban-American voters under age 45 by 26 points and lost those over age 45 by 29 points.