Croatia holds a referendum on Sunday on whether to join the European Union in 2013, with its leaders making clear the small Adriatic country has no better option despite the economic turmoil in the bloc.
Opinion polls suggest the vote will pass, with the last one, released on Saturday, putting support at 61 percent.
Supporters say a "No" vote would leave Croatia stuck with struggling fellow ex-Yugoslav republics in the western Balkans, which was ravaged by war in the 1990s and is the only part of southeastern Europe still outside the EU.
But some Croats fear a loss of sovereignty if the country joins now, after just two decades as an independent state.
"Croatia will not lose its sovereignty or natural resources, nor will it be ruled by the EU," President Ivo Josipovic said in a written statement to the nation on Saturday.
"Europe will not solve all our problems, but it's a great opportunity."
The European Union has said Croatia can become its 28th member on July 1, 2013 after completing seven years of tough entry talks in June last year. It would become the second former Yugoslav republic to join, following Slovenia in 2004.
The "No" camp is playing on fears of a wave of foreigners buying up Croatian companies and property. Some say the timing is all wrong and that the EU is not what it once was given the debt crisis that is threatening the single currency.
Many complain they are unsure what membership will mean for the country of 4.3 million people.
"My son is all excited and in favour, but I'm not," said Jasna, a 46-year-old hairdresser from the capital, Zagreb. "There are just so many things I don't know and don't understand about the EU that I cannot vote 'Yes'."
The "Yes" camp this week won the endorsement of Croatia's powerful Roman Catholic church as well as a former wartime general on trial for war crimes but regarded by many Croats as a national hero.
"I will vote for membership of the EU because that's where we belong," Ante Gotovina told state news agency Hina through his lawyers from the U.N. war crimes tribunal in The Hague.
Croatia broke away from Yugoslavia in a 1991-95 war, and then saw strong growth on the back of foreign lending and waves of tourists to its stunning Adriatic coast.
But its economy has been hit hard by the global economic crisis. Analysts and government officials warn a rejection of EU accession on Sunday would bring down the country's credit rating, deter investors and further dampen any prospect of a quick economic recovery.
If the referendum passes, all EU member states must ratify Croatia's accession before it can join. It will not join the euro zone yet.
Croatia's current GDP per capita is 61 percent of the EU average. It expects some 450 million euros, or 1 percent of its GDP, from EU funds for development projects in the first year alone.
"Croatia does not have, and will not have any time soon, the money to build infrastructure, develop rural areas and finance labour market reforms," said Zdravko Petak, a professor of political science in Zagreb.
"The only thing that can kickstart Croatia's growth is European money," he said.
Voting starts at 7 a.m. (0600 GMT) and ends at 7 p.m. (1800 GMT). First results are expected around an hour after polls close.