The European Union's newest member state, Croatia, is holding a snap election this weekend that pits the dominant parties on the left and right against each other but is unlikely to produce a clear winner. The uncertainty is fueling fears of prolonged instability that could hamper reform.

Here is a brief look at Sunday's vote.

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WHY THE SNAP VOTE?

Croatia's previous, right-wing government collapsed last spring after only six months in power, paralyzed by internal bickering among the coalition members. That government, led by a nonpartisan businessman from Canada, was formed after an inconclusive election last November.

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THE MAIN CONTENDERS

The main parties in Croatia are the left-wing Social Democrats and the right-wing Croatian Democratic Union, commonly known as HDZ. The parties have dominated Croatia's political scene since it split from Yugoslavia in the 1990s, but they will likely depend on smaller, kingmaker groups such as pro-reform Most.

The Croatian Democratic Union led Croatia during the 1991-95 war for independence and is viewed as nationalist.

The Social Democrats — running in a People's Coalition with some smaller groups — are considered successors to Croatia's Communists, who fought against Nazis during World War II and later ruled Croatia while it was part of the Yugoslav federation.

Most, a little-known group formed before last November's elections, came out of the last vote as a kingmaker. It formed a government with HDZ, but it didn't work well and the coalition government collapsed.

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WHAT'S AT STAKE

Although part of the campaign centered on past ideological divisions, whoever forms the next government will face some hard work on reforming Croatia's economy so it can catch up with the rest of the EU nations. Croatia has one of the weakest economies in the EU partly because of the war and delayed transition.

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ELECTION DAY

Croatia has 3.7 million voters. Polls open on Sunday at 0500GMT and close 12 hours later. Preliminary results and projections will start coming in an hour or two after the polls close. Official results are unlikely before Monday.