French voters have put President Emmanuel Macron's party on course for a crushing parliamentary majority, reflecting a huge blow for the mainstream parties.
Projections showed Macron widening his support, with his Republique en Marche (Republic on the Move, REM) party and its ally MoDem tipped to win between 400 and 445 seats in the 577-member National Assembly in next Sunday's second round. A minimum of 289 seats is required to secure an absolute majority. Such a share would give Macron one of the biggest parliamentary majorities seen in the modern French state.
"France is back," Prime Minister Edouard Philippe declared triumphantly.
The nationalist National Front (FN) of Marine Le Pen was meanwhile forecast to garner only between one and 20 seats.
The FN's result showed the party struggling to rebound from Le Pen's bruising defeat by Macron in May's presidential run-off.
The FN's deputy leader Florian Philippot admitted to "disappointment" and called on voters to "mobilize massively" for the second round.
The radical-left France Insoumise (France Unbowed) party of Jean-Luc Melenchon, who finished fourth in the presidential race, also fell short of expectations. His camp is tipped to only take 10-20 seats.
The worst losses, however, were for the Socialists of Macron's predecessor Francois Hollande and their allies, who are predicted to lose a staggering 200 seats.
The party's chief Jean-Christophe Cambadelis and its failed presidential candidate Benoit Hamon both crashed out of the running on Sunday.
Cambadelis appealed to voters not to give Macron a monopoly on power.
Parliament risked having "no real oversight powers and no democratic debate worth speaking of," he warned.
Few candidates reached the 50-percent mark needed for election at the first round.
A second round of voting will be held on Sunday in nearly all constituencies between the two or three top-placed contenders.
Official final results showed Macron's one-year-old REM and allies MoDem winning 32.32 percent, ahead of the Republicans on 21.56 percent and the FN on 13.20 percent.
The Socialists and their allies secured just 9.51 percent while the radical left and communists were on 13.74 percent.
German Chancellor Angela Merkel congratulated Macron on a "great success" Sunday, calling it "a vote for reforms."
Sunday's results show he will have relatively free rein to push through the ambitious labour, economic and social reforms he promised on the campaign trail.
Government spokesman Christophe Castaner said the 49 percent turnout, the lowest since the 1950s in such a vote, was "a failure of this election", acknowledging that the Macron team would need to reach out to those who stayed away. Former prime minister Alain Juppe of the center-right Les Républicains however said the low turnout was a sign of "deep malaise" in the electorate and that a clean sweep by Macron would be bad for democracy. "The stakes of the second round are clear," said the current mayor of Bordeaux, calling for Republicans voters to turn out in force on Sunday. "Having a monochrome parliament is never good for democratic debate".
Among commentators also sounding a cautionary note was Nicolas Beytout of the daily L'Opinion, who wrote: "Sure, Emmanuel Macron is ready to pull off the unthinkable for someone who didn't even have a party a year ago - a spectacular majority in the National Assembly."
Macron's score of 24 percent in the first round of the presidential race and Sunday's low turnout undermine "the illusion of Macron-mania," he said.