In his two years in President Francois Hollande's government, 38-year-old Macron confronted Socialist orthodoxy head-on, questioning the 35-hour work week -- a totem of the French left.
His business-friendly policies riled many leftist colleagues and activists.
During a public outing in June, trade unionists pelted him with eggs.
But the swipes at the man dismissed by one veteran Socialist as a "start-up" politician have failed to dent his ambitions.
"If approval was a criterion in this country, nothing would ever get done," Macron said last year.
His willingness to defy convention -- saying he is "neither of the left or the right" -- also extends to his personal life.
At 16, he fell in love with a teacher from his high school -- a woman some 20 years his senior -- and they have been married since 2007.