PARIS (Reuters) - Emmanuel Macron’s party is set to win the biggest parliamentary majority for a French president since Charles de Gaulle’s 1968 landslide, a survey of voter intentions for the coming legislative elections showed on Tuesday.

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Such a majority would give Macron’s government a strong mandate to push ahead with economic reforms, starting with a pro-business overhaul of France’s labor code, a notoriously difficult area of policy to agree with trade unions.

(For a graphic on Election, click tmsnrt.rs/2rWjPPp)

Macron’s centrist Republic On The Move (LREM) party, which launched in April last year and has revolutionized the French political scene, was seen scoring 29.5 percent of the vote in the June 11 first round, the Ipsos Sopra-Steria poll found.

With a solid lead ahead of other parties, LREM would go on to win 385-415 seats out of 577 in the lower house of parliament in a June 18 second round of voting, the poll showed.

The projected majority fits with a Cevipof survey for Le Monde on Friday, and would be the strongest since voters rallied behind former president and wartime hero De Gaulle in 1968 after student revolts and nationwide general strikes.

The conservative Republicans and their allies were seen at 23 percent, with the National Front on 17 percent, the hard-left France Unbowed 12.5 percent and the Socialists 8.5 percent.

LREM’s first round lead has narrowed from 31 percent the last time the poll was conducted a week ago after Macron’s former campaign chief - now a cabinet minister - came under investigation for past financial dealings.

The investigation into the activities of Richard Ferrand took a new turn on Tuesday as a media report said investigators had raided a business headquarters linked to their inquiries.

But that has so far done little to dent Macron’s popularity after he beat the National Front’s leader Marine Le Pen. Sixty percent of those surveyed said they were satisfied with Macron.

And, after the first round eliminates any candidate who gathers less than 12.5 percent of the vote, Macron’s candidates will be strongly placed across the country to win the decisive second round, pollsters say.

In the second round, the poll projected that The Republicans party would win just 105-125 seats in parliament, the Socialists 25-35 seats, France Unbowed 12-22 seats and the National Front 5-15 seats.

The poll, conducted on June 2-4 for France Televisions and radiofrance with a sample of 2,103 people, also found that 68 percent of those surveyed had definitely made up their minds about whom they would vote for.

That rose to 75 percent for those backing Macron’s party.