Marine Le Pen said her party would struggle to make payroll following a financial scandal.
Around half of En Marche's candidates are political newcomers, with the average age under 50.
The French far-right leader could perform poorly in parliamentary elections.
While some may have been pushed to "fight against those who speak badly about Russia," the Russian president denied claims that his government has hacked foreign elections.
The joke planned by campaigners for Francois Fillon involved fake glasses that mocked his prominent eyebrows.
The Freedom Party pursues a policy of "Austria first," and is opposed to Islam and immigration.
In his first words after taking office, he pledged to restore France's standing on the world stage, strengthen national self-confidence and heal divisions that the bitterly-fought campaign had opened up.
Populist politics are likely to remain in the mainstream despite Le Pen's defeat, the third blow in six months to Europe's far right.
Despite the palpable relief at the result in Brussels, Macron's margin victory was in fact uncomfortably small.
The fight is only just beginning for France's new president.
In France's most tumultuous election in years, political uncertainty looks set to continue, whoever wins.
There is a burgeoning divide between the working middle class and the gilded Parisian super-rich.
The data leak emerged as polls predicted Macron, a former investment banker and economy minister, was on course for a comfortable victory over far-right leader Marine Le Pen in Sunday's election.
Marine Le Pen has a mountain to climb going into the final hours of her presidential race against Emmanuel Macron.
The independent candidate is predicted to win 62 percent of the votes on Sunday.
People in France really, really don't like Donald Trump, who's spoken favorably of far-right presidential hopeful Marine Le Pen.