ATHENS - Greek parliament deputies vote on Monday on a bribery scandal that has rocked the conservative government for months and may prompt a snap election as Greece struggles with a slowing economy and social unrest.

Defections in his one-seat parliamentary majority could force Prime Minister Costas Karamanlis to call an election more than two years early to coincide with a June 7 European Parliament ballot.

The government walks a tightrope, wrote the conservative Eleftheros Typos daily. A double election on June 7 would obviously distract the country from dealing with the crisis.

Discontent with Greece's slowing economy and high youth unemployment fueled the country's worst riots in decades in December, after police shot dead a teenager in Athens.

Parliament will vote on whether Aristotle Pavlides, a ruling New Democracy party MP and former minister for the Aegean, must stand trial on bribery charges. He denies any wrongdoing and has resisted pressure to resign his seat.

The case was brought to light by a shipowner who testified that a Pavlides aide demanded bribes to grant a contract to run subsidized Aegean island ferry routes.

A committee of Greek MPs failed to reach agreement on the case last week, leaving the decision to the full house. All opposition parties have asked deputies to vote against Pavlides, while New Democracy supports its deputy but has allowed its MPs to cast a blank ballot, fearing outright dissent.

More than Pavlides's fate hangs in the balance. New Democracy has 151 deputies in the 300-seat parliament and although it would not immediately lose its majority if Pavlides was sent to court, it would find it hard to govern relying on a deputy on trial.

After five years in power, the government trails the socialist opposition in opinion polls, shaken by scandals -- from controversial land swaps between the state and a monastery to suspect government bond sales to state-run pension funds.

At stake is our will to fight corruption, said socialist PASOK party leader George Papandreou. The image of a government held hostage by corruption hurts all of us.

Karamanlis has accused PASOK of populist rhetoric in the face of the crisis and vowed to stay the economic policy course.

Those who covered up scandals worth millions, now appear as preachers of morality, he told a rally on Sunday. PASOK cultivates a sick climate that poisons public life.

The vote comes as the government, under EU pressure to cut deficits and debt, has launched unpopular tax and wage measures to cope with the economic crisis.