The 38-year-old economy minister set up "En marche" (On the move) in April to the consternation of many of his Socialist Party colleagues.
They saw it as a challenge to the authority of embattled President Francois Hollande.
The timing of his speech on Tuesday, two days before Hollande gives his traditional Bastille Day TV interview, has also raised some eyebrows.
Macron's allies say though that no-one should expect him to announce yet that he is either leaving the government or that he will be a candidate for president.
"He is not going to say 'I'm leaving straight away'" but he is "entering campaign mode", said one of Macron's main supporters, the mayor of Lyon, Gerard Collomb.
Some say he could launch his real campaign in September, France's traditional back-to-work month after the summer holidays.
Macron hinted again at the weekend that he had ambitions to stand in next May's election.
Invited to watch a stage of the Tour de France, he made a series of references comparing cycling with politics, saying he was in the race to challenge for the "yellow jersey" worn by the leader.
"There are several stages. One began on April 6 (with the creation of En Marche) and I hope to see it through to the summit," he added in a reference to the mountainous stage of the race.
The problem for the Socialists is that while Macron refuses to rule out a bid for France's highest office, Hollande's abysmal poll ratings make it hard for him to appear the natural candidate of the left 10 months from now.
In an apparent jibe at Hollande, Macron said this month the possibility of primaries being held to decide the candidates of both the Socialists and the centre-right Republicans was "proof of the weak leadership on both sides".
Hollande has said he will decide by the end of the year whether he will stand, even though opinion polls currently show he would be eliminated in the first round.
The president and the government appear to have weathered the storm of weeks of strikes and protests over their attempts to reform France's rigid labour laws to make it easier to hire and fire employees and bring down the high unemployment that has dogged Hollande for four years.
France's successful staging of the European football championship also gave Hollande some relief from his critics, even if the host nation lost to Portugal in the final on Sunday.
Hollande's response to Macron's setting up of the party in April was clear -- he "has to be in my team, under my authority", he said.
"It's a question of personal and political loyalty," the president added.
Applauded by liberals for challenging the key planks of French Socialism such as the 35-hour work week, Macron has been lampooned by die-hard leftists as being too cosy with big business.
He earned nearly €1 million ($1.1 million) a year as a Rothschild banker before entering politics as an advisor to Hollande, who named him to the cabinet in August 2014.
France is also fascinated by Macron's marriage to his wife Brigitte, 20 years his senior, whom he met when she was teaching at his high school. She plays a prominent role in the running of his office.