Elections for the 577 seats in the lower house National Assembly are a two-round process, with the shape of the new parliament becoming clear only after the second round on June 19.

The ballots provide a crucial coda to April's presidential election, when Macron won a second term and pledged a transformative new era after a first mandate dominated by protests, the coronavirus pandemic and Russia's war against Ukraine.

After a dismal performance in April, the French left has united in a coalition for what its leader Jean-Luc Melenchon dubs "the third round" of the presidential elections.

Opinion polls show the president's centrist alliance, Ensemble (Together), and Melenchon's NUPES coalition of hard left, Socialists, Communists and Greens neck-and-neck in the popular vote -- although the actual breakdown of parliamentary seats will depend on turnout in the second round.

'Gardening instead'

The abstention rate is predicted to be well over 50 percent in the first round, in what would be a new record for elections already marked by feeble participation in recent years.

At midday (1000 GMT) turnout was 18.43 percent, according to an interior ministry estimate, down 0.8 points from the last election in 2017.

"I voted tactically in the presidential election, and that didn't change a thing," unemployed 59-year-old Alain Mendez told AFP at an outdoor cafe in Toulouse, southwestern France. "So today I'd rather do my gardening instead, and cook for my grandchildren."

If the president's alliance retains an overall majority, Macron will be able to carry on governing as before.

Falling short could prompt messy bill-by-bill deals with right-wing parties in parliament, or an unwanted cabinet reshuffle.

A win by the left-wing alliance  seen as unlikely by analysts would spell political disaster for the president by raising the spectre of a clunky "cohabitation" -- where the prime minister and president hail from different factions.

Such a set-up has has paralysed French politics in the past, most recently from 1997 to 2002 when right-wing president Jacques Chirac ruled in tandem with Socialist Lionel Jospin as premier.

Melenchon, a former Marxist, has already made clear his ambition to become prime minister and stymie Macron's plan to raise the French retirement age, a key part of his reform plans.

 'Can't get anything done' 

Polls have indicated that Macron's alliance is expected to win the largest number of seats but is by no means assured of getting over the line of 289 for an absolute majority.

"Some people say that parliamentary elections aren't important but that's not true," Arnaud, a 40-year old engineer, told AFPTV as cast his vote in central Paris. "If the president doesn't win a majority he can't get anything done."

While Macron and his European Union allies breathed a heavy sigh of relief after his solid, if unspectacular, presidential victory against far-right leader Marine Le Pen, the last weeks have brought no sense of a honeymoon.

Energy and food prices are soaring in France as elsewhere in Europe, the treatment of English fans at the Champions League final in Paris damaged France's image abroad and Macron has been accused by Ukraine of being too accommodating to Russia.

His new Disabilities Minister Damien Abad has faced two rape accusations which he has vehemently denied  while new Prime Minister Elisabeth Borne has yet to make an impact.

Macron has made clear that ministers who are standing in the election including Borne, who is making her first attempt at winning a seat -- will have to step down if they lose.

Macron's party and his allies currently hold an absolute majority of 345 seats in the 577-seat assembly.

Under France's system, a candidate needs over half the vote on the day as well as the backing of at least 25 percent of registered voters in a constituency to be elected outright in the first round.

Otherwise the top two candidates in a constituency, as well as any other candidate who won the backing of at least 12.5 percent of registered voters, go forward to the second round, where the candidate with the most votes wins.