Macron's Republic on the Move (LREM) last week lost its outright parliamentary majority after 17 MPs defected, although officials insisted the party will have no problem pushing through legislation.
The seven latest MPs to leave will join a new faction called “Agir Ensemble” (Act Together), which will be the 10th parliamentary grouping in France's National Assembly, a record number in modern France.
They said the new faction – while remaining loyal to the LREM – would be “agile” and in a position to shake things up after the coronavirus passes.
The move lowers the number of LREM MPs in the chamber to 281, short of the absolute majority of 289.
The party enjoyed a wide majority, with 314 MPs, following 2017 parliamentary elections in the wake of Macron's rise to power.
However, the majority has been steadily eroded, a process that has sped up in recent weeks even though the LREM still retains the support of the centrist MoDem faction.
The head of the new faction, Olivier Becht, insisted that the new formation was not in opposition and would “support the action of the president” and be a “third pillar of the majority” alongside LREM and MoDem.
A government source shrugged off the latest changes, saying the Act Together faction would be “absolutely loyal to the majority and a supplementary pillar”.
However another source said that Prime Minister Edouard Philippe had criticised the move at an online meeting with LREM MPs.
Macron is facing re-election in 2022 in what many analysts expect will be a two-horse race with far-right leader Marine Le Pen.
An Odoxo opinion poll published Tuesday said Macron's popularity had plunged seven points to 35 percent over the last month, almost wiping out gains he had made at the helm of France's coronavirus fightback.
Last week 17 members of LREM party said they had formed a new political grouping named “Ecology, Democracy, Solidarity” (EDS) to pursue greener policies, “modernise” the political system, and reduce social inequalities.