French voters go to the polls on Sunday in the first of two rounds that will decide whether President Emmanuel Macron gets a working majority in parliament or ends up without the support needed to drive through his reform agenda.

Less than two months after reelection, Macron faces a strong challenge from a united left-wing bloc that polls show could deprive the president of an outright majority even if it does not take control of parliament.

Government insiders expect a rather poor showing in Sunday's first round for Macron's coalition "Ensemble," with record numbers of voters seen abstaining. Hard-left firebrand Jean-Luc Melenchon's bloc hopes to capitalize on anger at the rising cost of living.

"I voted for hope ... so not for our current president," said Michel Giboz, 71, after voting for Melechon's New Ecologic and Social People's Union (NUPES) bloc at the poll station located in the 18th Parisian district's town hall.

"We need to get rid of them (the president's party). This is the last hope to stay in a democracy, or what's left of it."

Ivan Warren, who voted for Macron in the presidential election, said it was important to hand him a majority.

"It's important to me that we have a strong government that allows us to represent France in the most effective way possible," the 56-year-old computer scientist said.

At risk is Macron's ability to pass his reform agenda, including a pension reform he says is essential to restore public finances. His opponents on the left are pushing to cut the pension age and launch a big spending drive.

"We expect a difficult first round. Voters will want to send a signal," a government source told Reuters. "But we're counting on the second round to show that Melenchon's program is fantasy."

Initial projections after the presidential election showed Macron was on course to get a majority in parliament. But the president has kept a low profile since the vote, taking two weeks to form a government and only rarely making appearances. Meanwhile, Melenchon has successfully forged an alliance between his France Unbowed movement, the Socialists and the Greens.

Projections now show Macron and his allies, including the new party of his former prime minister Edouard Philippe, could fall short of a majority of 289 by as many as 40 seats.

Some 14 of Macron's ministers are competing in local races and could lose their job if they fail to win a seat.

One Cabinet member most at risk is Clement Beaune, Macron's Europe minister, who is campaigning in an eastern Paris constituency. As a former adviser on matters such as Brexit, Beaune, 40, is a close ally of the president.

"That would be a painful loss," a government source said.

On the other side of the political spectrum, polls show far-right leader Marine Le Pen could win a seat in her northern constituency from the first round, by gaining over 50% of the votes.