French president-elect Emmanuel Macron and his wife Brigitte sing the national anthem with supporters. Macron made good on his promise to promote political novices in En Marche's slate of parliamentary candidates | Eric Feferberg/AFP via Getty Images Emmanuel Macron gambles on novices for parliament More than half the En Marche candidates have never held public office and the average age is 46.

PARIS — Emmanuel Macron’s En Marche movement published a long list of candidates for next month's parliamentary elections that gave flesh to the French president-elect’s pledge of political renewal — while leaving the door open for a few more days to conservative Républicains MPs who are tempted to defect.

Addressing the hottest issue this week in French politics, Richard Ferrand, secretary-general of the movement created by Macron a year ago, said it wouldn’t field a candidate in at least one of France’s 577 electoral districts — the suburban Paris seat of former Socialist Prime Minister Manuel Valls.

By declining to formally endorse Valls or fight him in the polls, Macron wants to signal that “one simply doesn’t shut the door on a former PM who wants to help,” Ferrand said.

Earlier this week, Valls said he would run under the En Marche banner, prompting a rush of comments from the movement's spokespeople that he “didn’t fit the criteria” — namely, that he hadn’t gone through the online application process imposed by Macron. Some of them fear that Valls, an unpopular prime minister who resigned last year to seek the Socialist presidential nomination, might cost more votes than he would help attract.

En Marche released the names of 428 candidates and said the rest would be made public next week. Ferrand acknowledged this was aimed at giving more time to conservative lawmakers who are tempted to back Macron. Many of these moderate Républicains figures are waiting for Macron to name his prime minister to gauge whether he will stick to his promise to govern with politicians from all persuasions.

En Marche released the names of 428 candidates and said the rest would be made public next week.

Macron is unlikely to announce his choice for PM before he officially takes over from outgoing President François Hollande on Sunday.

Bruno Le Maire, the former conservative minister who has been the most vocal in his intention to work with Macron, said that he expected the appointment of a prime minister from the centrist wing of the Républicains party. En Marche pointedly didn’t name a candidate in Le Maire’s district in Normandy.

It also refrained from announcing a candidate against Gilles Boyer, who managed Bordeaux Mayor Alain Juppé's campaign for the conservative primaries and is now running for parliament for the first time in a district near Paris.

Boyer’s close friend Edouard Philippe, the conservative mayor of Le Havre and another Juppé ally, is widely rumored to be on Macron’s short-list of possible prime ministers.

Overall, the existing list of En Marche candidates illustrates both the scope of the Macron political experiment and its inherent risks: It includes only a few nationwide personalities, and makes good on Macron's promise to promote political novices, made in January when he set the criteria for his MPs.

Of the candidates named so far, 52 percent have never held elected office. Their average age — 46 — is 14 years younger than that of MPs currently sitting in the National Assembly, parliament's lower house. Ferrand said the nine-person committee tasked with picking candidates received about 19,000 online applications since the launch of the process in January.

So far, only 24 sitting MPs — less than 6 percent of the total — have made the list, all of them from the Socialist Party. "Many" were rejected, said Ferrand.

The remainder of the candidates will be announced by Wednesday next week. By then, Macron will have appointed his PM and his cabinet, which he has promised will be gender-balanced and restricted to 15 ministers.