WASHINGTON — The surprise announcement by President Obama on Wednesday that the United States and Cuba will move to restore full diplomatic relations could complicate one of the most enduring fault lines in American politics and reshape the fight to win the presidential battleground state of Florida.  For more than a generation, Republicans have offered a consistent hard-line anthem against the Communist nation, endearing themselves to the politically potent bloc of Cuban-Americans who have been crucial in deciding elections in the state. But those animosities have given way as younger voters with family ties to Cuba but no direct memories of the island under Fidel Castro have been more willing to support Democrats.  “Each day that passes, the proportion of the Hispanic electorate that comes from embargo-era Cubans shrinks, and they are now vastly outnumbered by an explosion of new Puerto Rican voters,” said Steve Schale, a Democratic strategist in Florida who worked on Mr. Obama’s campaigns there in 2008 and 2012. “Moreover, the grandchildren and now great-grandchildren of those embargo-era Cubans have a more open view toward the Cuban question.”  President Obama discussed the release of the contractor, Alan P. Gross, who had been held in Cuba for five years, as well as the release of an intelligence agent held for nearly 20 years.  That is not the way some Republicans considering a run for president in 2016 see it. They harshly criticized Mr. Obama, even as they praised the release of the imprisoned American Alan P. Gross.  “This entire policy shift announced today is based on an illusion, on a lie, the lie and the illusion that more commerce and access to money and goods will translate to political freedom for the Cuban people,” said Senator Marco Rubio, Republican of Florida, who called the president “the single worst negotiator we have had in the White House in my lifetime.”  “All this is going to do is give the Castro regime, which controls every aspect of Cuban life, the opportunity to manipulate these changes to perpetuate itself in power,” added Mr. Rubio, a Cuban-American.  He also promised to use his perch in the next Congress as chairman of the Senate Foreign Relations subcommittee on the Western Hemisphere to try to prevent the policy from moving forward, with a veiled warning to the White House. “We’re going to have a very interesting couple of years, discussing how you’re going to get an ambassador nominated and how you’re going to get an embassy funded,” Mr. Rubio said.  Wednesday’s news also offered an early glimpse into the challenges facing Jeb Bush, the former Republican governor of Florida, who announced Tuesday that he would explore a 2016 presidential run. Mr. Bush, in a Facebook post, called the moved toward normalized relations “the latest foreign policy misstep by this president and another dramatic overreach of his executive authority.”  “It undermines America’s credibility and undermines the quest for a free and democratic Cuba,” he wrote. “The beneficiaries of President Obama’s ill-advised move will be the heinous Castro brothers who have oppressed the Cuban people for decades.”  The question for Republicans is how well that sentiment resonates, most notably in Florida. A poll of Cuban-Americans in Miami-Dade County conducted this year by Florida International University found that 68 percent were open to the possibility of restoring diplomatic relations between the two countries, a number that rises to 88 percent among those younger than 30.  But the Hispanic population of Florida is increasingly multidimensional, with a large number of former residents of Puerto Rico and others from Latin and South America, for whom the issue of Cuba is not paramount. This has been particularly true in the growing Orlando area; Mr. Obama’s victory in Florida in 2012 was powered in part by his sizable margins in two heavily Hispanic counties.  Indeed, after decades of ritual stops for strong Cuban coffee on Calle Ocho in Little Havana in Miami, candidates are spending more time in the Puerto Rican enclaves in and around Orlando. Even those results have not translated into a shift among most Republicans. “If you’re from Florida, the politics may have shifted, but not enough to make it worthwhile to change your position,” said John Feehery, a Republican strategist. “I think that the further you are from Florida, the more likely you’re going to think that this a good thing.”  In the race for governor this year, Charlie Crist, a Democrat, lost to the Republican incumbent, Rick Scott, but won the Hispanic vote, including the Cuban-American vote by a small margin.  Senator Robert Menendez of New Jersey, one of three senators with Cuban ancestry along with Mr. Rubio and Ted Cruz of Texas, was among the few Democrats to criticize the president. Mr. Menendez, chairman of the Foreign Relations Committee, warned that the exchange set a “an extremely dangerous precedent.”  Mr. Cruz, a possible Republican candidate for president in 2016, said Mr. Obama’s new Cuba policy had simply made the underlying problem “worse.”  “Fidel and Raúl Castro have just received both international legitimacy and a badly needed economic lifeline from President Obama,” he said.  Some Republicans backed the president. Senator Jeff Flake of Arizona, who flew to Cuba with several other lawmakers to accompany Mr. Gross back, said he supported Mr. Obama’s move and hoped he could persuade more Republicans to agree.  “The policy that we’ve had in place for the past 50 years has done more in my view to keep the Castro regimes in power than anything we could have done,” Mr. Flake said. “I think it will improve the lot of ordinary Cubans, and it’s good for Americans as well.”  He was joined in his praise by Representative Mark Sanford, Republican of South Carolina, who said he was willing to give the president “credit where credit is due.”  The hard-line stances by many of the 2016 Republican hopefuls also put them in opposition to the United States Chamber of Commerce, which said it “welcomes” the development, as well as Pope Francis, who worked behind the scenes to help secure Mr. Gross’s release.  Hillary Rodham Clinton, who advocated a normalization of relations with Cuba in her book “Hard Choices,” said in a statement on Wednesday, “Despite good intentions, our decades-long policy of isolation has only strengthened the Castro regime’s grip on power.”  Jim Webb, a former Democratic senator from Virginia who has announced a presidential exploratory committee, said in a Twitter message that Mr. Obama made the right decision on Cuba, comparing it to his own work toward the normalization of relations with Vietnam.  A version of this article appears in print on December 18, 2014, on page A15 of the New York edition with the headline: Change in Policy, Like Shift in Demographics, Could Alter Florida’s Political Map. Order Reprints| Today's Paper|Subscribe
Republicans who prize the Cuban-American vote in a battleground state criticized President Obama’s move, but a younger, more multidimensional Hispanic electorate has shown signs of being open to it.