The participation rate could help determine the size of the presidential majority, with a high turnout helping the Socialists.

The first-round parliamentary vote a week ago saw a record low voter turnout of barely 60 per cent.

Socialist crisis

The Socialists have been in crisis since the presidential election in May and have tried to played on the fear that a huge majority for Sarkozy would simply render parliament a rubber stamp for his policies.

Sarkozy's new government has already scheduled an extraordinary session of the new parliament for June 26 to begin passing some of his planned reforms.

Those include loosening the 35-hour work week, guaranteeing minimum service during public-transport strikes and getting tough on repeat lawbreakers and illegal immigration.

Over the two rounds of voting, independent centrists and extremist parties were likely to be the biggest losers.

The UDF party of Francois Bayrou was expected to win just 2-3 seats, the Greens 2-4, the Communists up to 16 and the far-right National Front none.

VAT fear

Sarkozy had urged voters to back his agenda for change with a powerful majority and his energetic start to his presidency has proven popular with voters and driven the right's campaign.

The first round saw 110 seats filled outright - all but one by UMP members - in constituencies where a single candidate took more than 50 percent of the vote. The 467 remaining seats went to the runoff.

Looking for a weak spot in the Sarkozy machine, the Socialists most recently seized on government hints of a possible sales-tax increase.

Socialist candidates hung signs in their offices: "June 17, Vote against the VAT at 24.6 percent."

The issue of a potential sales-tax increase, meant to help pay for social security, left Sarkozy disarmed for the first time since he took office May 16.

On Thursday, he publicly repudiated any sales-tax increase "that would reduce the buying power of the French".