Correction: ●An earlier version of this article incorrectly said Croatia would be the first former Yugoslav state to be admitted to the European Union. It would be the second; Slovenia became a member in 2004. This version has been corrected.

Croatian President Ivo Josipovic, right, and Prime Minister Zoran Milanovic raise glasses of champagne in front of a painting of the first Croatian Parliament as they watch the first results of the EU referendum on a TV screen in the Croatian Parliament building in Zagreb on January 22, 2012. (HRVOJE POLAN/AFP/GETTY IMAGES)

Croats voted Sunday to join the European Union, after a heated campaign that reflected how the economic turmoil of the past several years has damaged the prestige of membership.

Not long ago, becoming a member of the E.U. club was seen as a quick ticket to economic success, as borrowing costs dropped and investors swarmed some of the former Eastern Bloc countries that joined eight years ago. Now, the union is notable mainly for the financial upheaval that has threatened to spread across the Atlantic and affect growth in the United States as well as in Europe.

Still, citizens in some small countries appear to believe the European Union is still worth joining. With more than 99 percent of the ballots counted, Croatian officials said 66 percent of voters approved the referendum. Turnout was about 44 percent, which is considered low, they said. Assuming E.U. member countries approve Croatia’s entrance, the country by mid-2013 would be the union’s 28th member.

The union that Croats voted to join is far different from the one with which the country began negotiating its entrance more than six years ago. Then, the union seemed to promise prosperity. Now, that’s far from guaranteed.

“There was a debate whether we would be in a better position to deal with our economic problems if we are a member or not. This was not clear to the people,” said Nenad Zakosek, dean of the political science department at the University of Zagreb.

Other countries have chafed under the pressure of E.U. restrictions in recent years, especially those countries that bound themselves together even more firmly by adopting a single currency, the euro, which Croatia is still far from doing.

Greece’s future in the euro zone is in doubt as it struggles to put in place painful austerity measures that European leaders have demanded as a precondition to economic assistance. In Hungary, tens of thousands of people turned out in the streets of Budapest this weekend in a show of support for Prime Minister Viktor Orban, who has aggressively questioned the E.U.’s role in his country even as he tries to negotiate a new credit line with the International Monetary Fund to stabilize Hungary’s faltering economy.

And Britain, long a euro-skeptic, has been pushing against the European Union with renewed force in recent months, rejecting a new financial treaty that all 26 other members have agreed to in principle.

But for Croats who argued in favor of joining the union, the step will bring their country more influence and is a valedictory, of sorts, after the long, painful wars of the 1990s as the former Yugoslavia tore itself apart. Croatia would be the second of its once-warring neighbors to become an E.U. member. Slovenia joined the union in 2004.

“It’s a big moment in our history,” Croatian President Ivo Josipovic said after voting Sunday, the Associated Press reported. “We are joining more successful countries in Europe.”

Croatia’s first years inside the European Union could be difficult. The country will have to cut subsidies to its shipbuilding industry, a dominant feature of its economy, and other businesses will be subject to scores of new regulations. Some struggling E.U. members have blamed the tough requirements for their economic travails.