By Richard Lough and Brian Love
PARIS (Reuters) - President Emmanuel Macron's government on Monday promised to reshape France's political landscape after winning the commanding parliamentary majority he sought to push through far-reaching pro-growth reforms.
Macron's centrist Republic on the Move (LREM) party and its center-right Modem ally won 350 out of 577 lower house seats in Sunday's election, which marked a record low turnout for a parliamentary ballot in the postwar Fifth Republic.
Government spokesman Christophe Castaner said the high abstention rate -- more than 50 percent of voters stayed at home -- was a failure for the governing class and highlighted the need for a new politics.
"The real victory wasn't last night, it will be in five years' time when we have really changed things," Castaner told RTL radio.
He also said dissent would not be tolerated among the dozens elected on the Macron party ticket, including many newcomers such as 24-year-old law school graduate Typhanie Degois.
"Being a member of parliament for Republic on the Move is a commitment to Emmanuel Macron's presidential program. It's about loyalty," he said, adding that the previous Socialist government was dogged by dissenters pursuing personal goals.
Though lower than forecast by pollsters, Macron's majority swept aside France's main traditional parties, humiliating the Socialists and conservative The Republicans party that had alternated in power for decades.
"Victory for the Center" read the headline of the left-leaning Liberation newspaper. Financial paper Les Echos' banner read "The Successful Gamble".
Prime Minister Edouard Philippe and his government were set to resign later in the day or on Tuesday and form a new cabinet, which spokesman Castaner said he believed would again be led by Philippe.
Investors welcomed Macron's win, with the gap between French and German bond yields holding near its tightest level in seven months.
"After the reforms, which we expect Macron to implement, France could turn into the strongest of all major economies in Europe in the next decade, outclassing a Germany that is resting on its laurels and a UK that (through Brexit) is impairing its long-term growth prospects," said Holger Schmieding, chief economist at German bank Berenberg.
Macron wants to move quickly on relaxing labor regulations before overhauling France's unwieldy pension system next year.
During the presidential campaign he also promised to cut corporate tax to 25 percent from 33 percent and make a 50 billion public investment in energy, vocational training and transport infrastructure.
But he will need to be mindful of a budget deficit that the Bank of France forecasts will once again breach the EU cap of 3 percent of national income this year.
"It is in France's interests, its political credibility, its economic credibility, to conform with its obligations," Pierre Moscovici, the EU's French commissioner for economic and financial affairs told TV channel Public Senat.
Sunday's high abstention rate means Macron will also have to tread carefully with reforms in a country with muscular trade unions and a history of street protests that have forced many a government to dilute new legislation.
But with his wins in last month's presidential election and Sunday's parliament vote, he has routed the old political class.
France's youngest leader since Napoleon and having never before held elected office, Macron has seized on the growing resentment towards a political elite perceived as out of touch, and on public frustration at its failure to create jobs and spur stronger growth.
In winning the presidency in May, he filled a political vacuum created by disarray within the Socialist Party and the Republicans, with Sunday night capping a sequence of events that looked improbable a year ago.
The Republicans and their conservative allies will form the largest opposition bloc in parliament with 131 seats, while the far-right National Front won eight. The Socialist Party and allies won just 44, their lowest in decades.
"The collapse of the Socialist Party is beyond doubt. The president of the Republic has all the powers," Jean-Christophe Cambadelis said late on Sunday after announcing he would step down as party chief.
National Front leader Marine Le Pen promised her party would remain a source of strong opposition alongside other bigger parties, saying: "Don't write us off so fast."
Sunday's election saw a record number of women - 223 versus a previous high of 155 - voted into parliament, due largely to Macron's decision to field a gender-balanced candidate list.
(For graphic on French parliamentary election, click: http://tmsnrt.rs/2r9l3qw)
(Additional reporting by Caroline Pailliez and Helen Reid and Ingrid Melander; Editing by Andrew Callus and John Stonestreet)