ATHENS, Greece (AP) — Greece's lawmakers vote Wednesday in a crucial presidential election process that risks a government collapse if the sole candidate fails to win enough votes by Dec. 29. The vote comes amid stalled negotiations between bailed-out Greece and its international creditors. The renewed political instability has roiled international markets, sending Greece's borrowing costs spiraling and its stock exchange index plunging. There is scant chance that government nominee Stavros Dimas, a former EU commissioner, will win in Wednesday's first round, when he needs a two-thirds majority in the 300-member parliament. A second round is scheduled for Dec. 23, and a third on Dec. 29, when 180 votes are needed to avoid parliament being dissolved and early elections being called. Although lawmakers are voting for a president, the position is a figurehead and the true issue is whether to keep the coalition government in power or trigger early elections. Conservative Prime Minister Antonis Samaras' office issued a statement hours before the first round saying saying a vote for Dimas was not a vote for the government, but would mark a decision "to avoid a political adventure that could prove fatal to the country's European course." The left-wing opposition party, Syriza, has long called for early elections and has campaigned on promises to renegotiate Greece's deeply resented bailout commitments. That possibility, comments about reversing reforms and hints about the possibility of Greece not repaying debts have spooked international markets. Samaras announced last week he was bringing forward the presidential vote, originally scheduled for early 2015. The move raises a real possibility his government will fall about half way through its four-year term. For Dimas to win, Samaras needs to secure the backing of at least 25 independent or opposition lawmakers. So far less than 10 have declared they will support him.