French voters face a decisive choice Sunday in the runoff of snap parliamentary elections that could produce the country's first far-right government since the World War II Nazi occupation — or no majority emerging at all.

Marine Le Pen's anti-immigration, nationalist party National Rally stands a chance of winning a legislative majority for the first time, but the outcome remains uncertain because of a complex voting system and tactical maneuvers by political parties.

What's happening Sunday?

Voters across France and overseas territories can cast ballots for 501 of the 577 seats in the National Assembly, the lower and most important of France's two houses of parliament. The other 76 races were won outright in the first round of voting.

The National Rally and its allies arrived ahead in Round 1 with around one-third of the votes. A coalition of center-left, hard-left and greens parties called the New Popular Front came in second position, ahead of President Emmanuel Macron's struggling centrist alliance.

In the frantic week between the two rounds, hundreds of centrist and left-wing candidates pulled out of races to boost the chances of their moderate rivals and try to keep National Rally candidates from winning.

Final preelection polls suggest that tactic may have diminished the far right's chances of an absolute majority. But Le Pen's party has wider and deeper support than ever before, and it's up to voters to decide.

What are the possible outcomes?

Polling projections suggest the National Rally is likely to have the most seats in the next National Assembly -- which would be a historic first.

If it wins an absolute majority of 289 seats, Macron would be expected to appoint National Rally president Jordan Bardella as France's new prime minister. Bardella could then form a government, and he and Macron would share power in a system called 'cohabitation.''

If the party doesn't win a majority but still has a large number of seats, Macron could name Bardella anyway, though the National Rally might refuse out of fears that its government could be ejected in a no-confidence vote.

Or Macron could choose a prime minister from the center-left and seek to build a coalition with moderates.

If there's no party with a clear mandate to govern, Macron could name a government of experts unaffiliated with political parties. Such a government would likely deal mostly with day-to-day affairs of keeping France running.

Complicating matters: Any of those options would require parliamentary approval.

If political talks take too long amid summer holidays and the July 26-Aug. 11 Olympics in Paris, Macron's centrist government could keep a transitional government pending further decisions.

How does cohabitation work?

If an opposition force wins a majority, Macron would be forced to appoint a prime minister belonging to that new majority. In this 'cohabitation,'' the government would implement policies that diverge from the president's plan.

France's modern Republic has experienced three cohabitations, the last one under conservative President Jacques Chirac, with Socialist Prime Minister Lionel Jospin, from 1997 to 2002.

The prime minister is accountable to the parliament, leads the government and introduces bills.

The president is weakened at home during cohabitation, but still holds some powers over foreign policy, European affairs and defense and is in charge of negotiating and ratifying international treaties. The president is also the commander-in-chief of the country's armed forces, and holds the nuclear codes.

What about a hung parliament?

While not uncommon in other European countries, modern France has never experienced a parliament with no dominant party.

Such a situation requires lawmakers to build consensus across parties to agree on government positions and legislation. France's fractious politics and deep divisions over taxes, immigration and Mideast policy make that especially challenging.

That would likely derail Macron's promises to overhaul unemployment benefits or legalize life-ending procedures for the terminally ill, among other reforms. It could also make passing a budget more difficult.

Why is the far right rising?

While France has one of the world's biggest economies and is an important diplomatic and military power, many French voters are struggling with inflation and low incomes and a sense that they are being left behind by globalization.

Le Pen's party, which blames immigration for many of France's problems, has tapped into that voter frustration and built wide online support and a grassroots network, notably in small towns and farming communities that see the Paris political class as out of touch.

Why does it matter?

The National Assembly is the more powerful of France's two houses of parliament. It has the final say in the law-making process over the Senate, dominated by conservatives.

Macron has a presidential mandate until 2027, and said he would not step down before the end of his term. But a weakened French president could complicate many issues on the world stage.

During previous cohabitations, defense and foreign policies were considered the informal domain of the president, who was usually able to find compromises with the prime minister to allow France to speak with one voice abroad.

Yet today, both the far-right and the leftist coalition's views in these areas differ radically from Macron's approach and would likely be a subject of tension during a potential cohabitation.

Bardella said that as a prime minister, he would oppose sending French troops to Ukraine — a possibility Macron has not ruled out. Bardella also said he would refuse French deliveries of long-range missiles and other weaponry capable of striking targets within Russia itself.