Why France's legislative elections matter

France heads to the polls on Sunday for the second round of parliamentary elections.

President Emmanuel Macron's Ensemble (Together) alliance is seen ahead by opinion polls but with no guarantee of an absolute majority.

Here are key facts about this election.

WHY ANOTHER FRENCH ELECTION?

Macron, a pro-European centrist, won a second term as French president in April. But to maintain full control of his reform agenda, he also needs to win a majority in the lower house of parliament.

WHAT ARE THE POLLS FORECASTING?

Voter surveys had initially shown Macron's party and its allies - collectively known as Ensemble - winning an absolutely majority in the 577 seat parliament.

But that outcome has becomes less certain.

Polls show a leftist coalition led by hard-left veteran Jean-Luc Melenchon is unlikely to win the 289 seats required for an absolute majority but may secure enough to deprive Macron of the same.

WHY DOES THIS MATTER?

Falling short of an absolute majority would be a big setback for Macron. It would force him to broaden his alliance. The broader the alliance, the more complicated deal-making and dictating policy decisions would become.

A minority cabinet or coalition government would be an unusual scenario for modern-day France. The Fifth Republic was designed to avoid unwieldy coalitions.

If an opposition grouping were to surprise and win a majority, Macron would have to name a prime minister from the winning camp, ushering in a period of so-called cohabitation.

He would retain the lead on foreign policy but leave responsibility for most day-to-day policy matters to the government.

WHAT HAPPENS WHEN?

Only five lawmakers were elected in the first round last Sunday.

Voting for the run-off in the 572 other constituencies takes place between 8 a.m. and 8 p.m. (0600-1800 GMT) on June 19.

Polling for legislative elections is trickier than the presidential election as different dynamics on the ground make it harder to predict who will win nationwide.

WHAT DOES THE ELECTION LINE UP LOOK LIKE?

France's two mainstream centre-left and centre-right parties dominated the French political landscape until Macron's election 2017. Five years on both are still fighting for political relevance and the tectonic plates have shifted.

* Macron's party and his allies run under the banner of the centrist Ensemble alliance.

* Melenchon has gathered the Socialist Party, Greens and Communists behind his own La France Insoumise (France Unbowed) party in an unexpected show of unity on the left.

His Nupes alliance is second in polls.

* The conservatives, Les Republicains, hope to be the third biggest parliamentary group. Though they are forecast to be well behind Macron's camp and the left, they could become kingmakers if Ensemble has the largest group but not an absolute majority.

* Marine Le Pen's far-right Rassemblement National (National Rally) is polling third in terms of first-round votes, but fourth in terms of projected seats.