His party is changing its name to La Republique En Marche (Republic on the Move) as it prepares a list of candidates. "Marine must listen to that message", Gilbert Collard, part of Le Pen's inner circle and a member of an FN-affiliated political grouping, was quoted as saying in Le Parisien newspaper.
"As of today, he [Valls] does not fit the criteria that would allow the investiture committee to take him on, so., [until he joins] the national investiture committee that I preside over can not consider the candidature of Mr. Valls", Jean-Paul Delevoye, who chooses Macron's party's candidates, told Europe 1 radio yesterday.
The nomination process is a careful balancing act for Macron and represents major risks for his presidency, which will begin formally on Sunday when he takes over from outgoing Socialist Francois Hollande.
Mr Hamon, who gained popularity in recent years by leading a group of rebel Socialist lawmakers who opposed Mr Valls, was a distant fifth in the first round of the presidential election after garnering just over 6% of the votes, the Socialist Party's worst result since 1969.
May had called Macron to congratulate him on his election victory and the two leaders briefly talked about Brexit among other bilateral issues, Downing Street said. Mr Macron has promised that half of those candidates will be new to elected politics, as he was before his victory on Sunday.
No-one who planned to stand for the rightwing Republicans party has defected, party secretary general Bernard Accoyer said on Thursday despite efforts to recruit them.
"The National Front is a tool that will evolve to be more efficient, bring even more people together after the number of voters we reached last night". If another party wins a majority, Macron could be pressured to choose a prime minister from that party. Catherine Fabre, a middle-aged business management lecturer at Bordeaux University, told BFM TV earlier she was in the running and wanted to shake things up in a National Assembly which was, in her words, dominated by too many middle-aged white men.
She was openly critical of Marine Le Pen's score of 33.9 percent against Macron, reflecting the opinion of many critics of her aunt that a score of below 40 percent was a failure. In August 2014, Hollande named him economy minister within his Socialist government.
Hamon vowed to "rebuild the left" with a new "broad-based movement", while saying he meant to remain a member of the Socialist Party.