Greek shares are diving a day after the conservative-led government brought forward the date of a crucial presidential vote, raising a strong possibility of early general elections in the austerity-weary country.

The Athens benchmark general index was down 6.4 percent in early trading Tuesday, reflecting fears of protracted political uncertainty as Greece struggles to complete a painful financial turnaround.

Greece's president is a figurehead with minimal political clout. But the election requires a super-majority that would probably elude the struggling governing coalition. If three successive votes, from Dec. 17-29, prove fruitless, general elections must be called by early February.

The left-wing Syriza main opposition party is steadily leading polls, though without enough support to govern alone. Syriza opposes the international bailouts that saved Greece from bankruptcy in 2010.