The National Assembly in France has full powers to pass laws and approve the prime minister, and the country's two main parties - the Socialists and the Union for a Popular Movement - which for the first time were both absent from the second round of the presidential election, are seeking to use the vote to bounce back.
Benoit Hamon, the unsuccessful Socialist Party candidate in the presidential contest, said he would set up a new political movement after several of his hallmark proposals during that campaign were abandoned by his own party.
Macron has said half of the candidates for his year-old Republique en Marche (Republic on the Move) for the 577 seats up for grabs in 11-18 June elections will be new to politics.
An Elabe poll for BFM TV found that 52 percent of those polled wanted Macron's party to get a majority in parliament while 47 percent wanted opposition lawmakers to hold a majority. "It will be done in mutual understanding", he said.
The party was due later on Wednesday to work further on what Baroin said would be a revamped programme for the National Assembly election.
Mr Macron's campaign members Christophe Castaner and Benjamin Griveaux said Mr Valls is welcome but would have to go through the regular application process.
Showing who is in charge right now, his Republic on the Move party made clear on Wednesday that even top-rank politicians from established parties were not guaranteed a slot on its list of parliamentary contenders.
It comes as no surprise, then, that Macron's more decisive than expected victory has been hailed by most major news outlets across the world as a forceful rebuke of populism.
The former prime minister wants to run under the centrist president-elect's banner in the legislative elections.