Mr Macron, a 39-year-old centrist, is tipped to comfortably win a runoff vote against far-right leader Marine Le Pen, but the political movement he created a year ago faces a huge challenge in the follow-up legislative election in June.
With Mr Macron and his 'En Marche!' movement at risk of being in a minority in parliament, the centre-right party, The Republicans, hopes to secure enough National Assembly seats to demand a government role despite the defeat of its presidential contender Francois Fillon, eliminated in a first-round vote on April 23.
Francois Baroin, who served as a finance minister for former president Nicolas Sarkozy, on Wednesday publicly stated he was ready to work as prime minister in a 'cohabitation' arrangement with Mr Macron.
Mr Baroin, 51 and a rising star within The Republicans, said in an interview on CNews television, "I will be available to ... head the government according to the will of the French people."
Any power-sharing deal between Mr Macron and a right-wing prime minister, like that suggested by Mr Baroin, would likely impose big constraints on him in pursuing economic policies that seek to a balance state protection and pro-business reforms.
Before his exit, Mr Fillon derided Mr Macron's stated aim of being neither left- nor right-wing, pointing to the ex-banker's time as economy minister in the Socialist government of outgoing President Francois Hollande.
This judgment of Mr Macron is still strongly felt among many of the Mr Sarkozy-faction on the right-wing of The Republicans though others, loosely represented by more moderate ex-prime minister Alain Juppe, have suggested they may choose to join in a majority of support for Mr Macron.
Mr Baroin told CNews he would vote for Mr Macron on May 7 without hesitation but that he would not join in helping his campaign. He said he would throw his energy into campaigning for The Republicans in the June parliamentary election.
The last time France had a cohabitation arrangement between the Elysee and the government was from 1997 and 2002 when right-wing president Jacques Chirac had to work with a Socialist government under Prime Minister Lionel Jospin.
The arrangement curbed Chirac's day-to-day control over the direction of the economy, reducing him largely to looking after foreign policy and defence.
(Additional reporting by Emmanuel Jarry, Writing By Richard Balmforth, Editing by Brian Love)