Belgrade, Dec 17 : Polling stations are open as Serbia conducted extraordinary elections on Sunday, with citizens voting at parliamentary and local levels to decide state leadership for the next four years. Polling stations, numbering 8,273 both within Serbia and abroad, opened early Sunday morning. A total of 18 political parties or coalitions are vying for 250 seats in the national parliament, Xinhua news agency reported. The political parties or coalitions securing the highest votes can engage in negotiations to shape the upcoming government. A key requirement for entry into the parliament is achieving a minimum threshold of 3 per cent support. Pre-election polls indicate that the coalition aligned with the ruling Serbian Progressive Party, in power since 2012, is leading with nearly 40 per cent support, while the pro-Western opposition coalition follows next with around 26 per cent. /IANS