The National Rally (RN) and allies had 33 per cent of the vote, followed by a left-wing bloc with 28 per cent and French President Emmanuel Macron's centrists with just 20 per cent, official results from the interior ministry show.
That was a huge setback for Macron who had called the snap election after his ticket was trounced by the RN in European Parliament elections in May.
A left-wing bloc garnered 28 per cent of the popular vote, coming in second. (EPA PHOTO)
But whether the anti-immigrant, eurosceptic RN will be able to form a government will depend on Sunday's decisive round and how successfully other parties manage to thwart Le Pen by rallying around the best-placed rival candidates in constituencies across France.
French Finance Minister Bruno Le Maire on Monday ruled out calling on voters to choose a far-left candidate from the France Unbowed (LFI) party if that was the only realistic option to stop a candidate from the RN.
"LFI is a danger for the nation", Le Maire told France Inter radio, adding that while he'd encourage voters to pick candidates from other left-wing parties in places where a centrist candidate pulled out of the race, he'd "never" call for voting LFI.
Leaders of both the left-wing New Popular Front and Macron's centrist alliance made clear on Sunday night they would withdraw their own candidates in districts where another candidate was better placed to beat the RN in next Sunday's runoff.
Minister Bruno Le Maire said he would never call on voters to support the far-left France Unbowed. (AP PHOTO)
A longtime pariah for many in France, the RN is now closer to power than it has ever been. Le Pen has sought to clean up the image of a party known for racism and anti-Semitism, a tactic that has worked amid voter anger at Macron, the high cost of living and growing concerns over immigration.
An RN-led government would raise major questions over where the European Union was headed, given its resistance to further EU integration. Economists have also asked whether its spending plans are fully funded.
The euro touched a two-week high during Asian trading on Monday on market relief the RN had not done better.
RN lawmakers on Monday urged centre-right politicians in the Republicans (LR) party, which received less than seven per cent of the first-round vote, to withdraw from districts where such a move would work in RN's favour.
"If they know they're not going to win, I'm calling on them to stand down and let the national side win," RN lawmaker Laure Lavalette told RTL radio.
For now, the Republicans party, which split ahead of the vote with a small number of its lawmakers joining the RN, has given no indication of its stance.
All candidates who made it through the first round have until Tuesday evening to confirm whether they will go into the second.Â
