Former right-wing President Nicolas Sarkozy (2007 to 2012) called for Emmanuel Macron to be elected on Tuesday.
In the face of one of the “most serious international crises”, Macron alone has the necessary experience.
Sarkozy cited Macron's economic program with the central value of work and his European commitment as further reasons for voting on April 24.
"A new era begins.
It will require profound changes.
We must shed our habits and our partisan reflexes,” said Sarkozy.
He called on his party friends and supporters to join Macron's new political rally movement.
The Internet editorial team Mediapart, which specializes in research, had previously reported that Sarkozy is said to have already agreed with Macron on a minimum of 50 winnable constituencies in the parliamentary elections in June.
Macron is said to have promised him ministerial posts in the new government for people of his choice in return for his support.
Macron's campaign headquarters said on Tuesday that they would have liked a more discreet announcement.
Sarkozy is seen as a red rag by many left-wing voters.
Macron is wooing these left-wing voters, he had planned a rally in Strasbourg on Tuesday evening.
In the European city on the Rhine, Mélenchon took first place.
Criticism also rained down from Sarkozy's Les Républicains (LR) party.
The LR parliamentary group leader in the Senate, Bruno Retailleau, emphasized that Sarkozy's election recommendation was his "personal position" but not that of his "political family".
"We cannot rebuild the right by dissolving into Macronism," said the group leader.
“Nicolas Sarkozy wants a major reorganization with La Republique en marche.
The answer is no,” said LR MP Julien Aubert.
The chairman of the youth organization Young Republicans, Guilhem Carayon, announced that he would not vote for Macron.
"For five years we fought the policies of Emmanuel Macron," Carayon said.