French Prime Minister Edouard Philippe called for high turnout in this Sunday's parliamentary election which is expected to hand President Emmanuel Macron's new party an overwhelming majority.
Macron's year-old Republic on the Move (REM) party and its allies are tipped to win a landslide in the run-off election for the 577-member lower house of parliament.
Pollsters forecast them securing up to 470 seats, but low turnout in the first round has led critics to question the strength of the mandate for Macron's ambitious reform agenda.
In the first round, the abstention rate hit a nearly 60-year high of 51.3 percent and is forecast to rise to 53-54 percent in the run-off, much higher than the 44.6 percent in the last election five years ago.
"Go to vote!" Philippe said while campaigning in southern France late on Thursday. "It's the same message here as everywhere else: no one should abstain. In France voting is not obligatory... it is a right and a responsibility."
Sunday's results promise to deliver huge change to the National Assembly, bringing in a younger, more ethnically and socially diverse generation of lawmakers, many of whom are new to politics.
Macron, a 39-year-old centrist unknown to most people three years ago, looks on course to complete his stated aim of a "revolution" in French politics which few took seriously when he started in April last year.
"We've shot down everything that represented the system before and we're trying something else," said historian Didier Maus, who sits on France's Constitutional Council.
France is on course for the "biggest overhaul of its political figures since 1958 and perhaps 1945," he said.
REM has fielded a mix of centrists and moderate left- and right-wingers drawn from France's established parties, as well as complete newcomers including a star mathematician and a former bullfighter.
A new poll published on Thursday underlined the scale of the losses for France's main right-wing Republicans party and Socialists who have dominated French political life for decades.
REM and its allies were tipped for 440-470 seats, the Republicans and its allies for 70-90 seats and the Socialists 20-30 seats -- a loss for them of more than 200 after their five years in power under president Francois Hollande.
"The main parties of government are going to suffer with these results," Flore Santisteban from the Cevipof political research institute at Sciences Po university in Paris predicted.
The Socialist party is considering selling its headquarters in one of the most expensive areas of Paris to compensate for the huge fall in donations and public subsidies linked to its rout.
The survey by Opinionway Orpi also forecast disappointment for the far-right National Front. It was forecast to win no more than five seats, far below expectations for the party led by Marine Le Pen -- the rival Macron defeated for the presidency in May.
A new radical left party France Unbowed led by firebrand Jean-Luc Melenchon was forecast to win five to 15 seats along with its Communist Party allies.
Some analysts believe their best hope is that voters might turn out in greater numbers on Sunday to try to stop REM securing too large a majority which mean almost no opposition to Macron's agenda.
"There might be a correction," said Emmanuel Riviere from the Kantar Sofres polling group.
Many opposition leaders have stressed the danger of Macron facing little opposition or scrutiny from parliament under a constitution that confers huge powers to the president.
Melenchon said Friday that Macron lacked legitimacy. "How can you imagine that the population, half of which didn't go to vote... agrees to the directives that are the result of this situation? They won't agree," he warned on Friday.
Socialist party leader Jean-Christophe Cambadelis, one of many party heavyweights who lost his seat in the first round of voting on June 11, has warned that the opposition "will either be in the media or on the street."
And right-wing former prime minister Jean-Pierre Raffarin has urged voters to remember that "we are not electing an emperor".
Macron, a fervently pro-European moderniser, has set reforming France's rigid labour code, overhauling the national education system and introducing a new law to raise ethical standards in public life as his immediate priorities.
The vote on Sunday will cap a presidential and parliamentary election sequence which started in November last year with a primary to pick the candidate of the right-wing Republicans party.