Montenegrins are voting in a parliamentary election that could determine whether the small Balkan state continues on its Western course or turns back to its traditional ally Russia.

The vote Sunday pits the long-ruling pro-Europe Democratic Party of Socialists, led by powerful Prime Minister Milo Djukanovic, against a cluster of pro-Russian and pro-Serbian opposition groups that staunchly oppose the country's NATO bid.

The country of 650,000 people, squeezed between the Adriatic Sea and towering mountains, is deeply divided among those who favor and oppose Western integration.

Pre-election polls have predicted the closest race since Montenegro gained independence from much larger Serbia a decade ago.

Montenegro had been a faithful ally of Russia. But after splitting with Serbia in a 2006 referendum, Montenegro took a strong turn toward Euro-Atlantic integration.