Paris - Eleven candidates have been approved to run for French president, the country's Constitutional Council has announced, a month before the vote.
Pollsshow Macron and Le Pen establishing a clear lead in terms of voting intentions in the first round, while conservative candidate Francois Fillon, the one-time front-runner who has been damaged by a financial scandal, has slipped back.
Macron now holds the lead in the polls - followed closely by Le Pen.
Opinion polls show nearly 40 percent of voters are not completely sure who to back in the election, being held over two rounds on April 23 and May 7 against a backdrop of high unemployment and sluggish growth.
The other two candidates taking part in Monday evening's debate are the ruling Socialist Party's candidate Benoit Hamon and Jean-Luc Melenchon, who have split the left-wing vote.
The five leading candidates for France's presidential election are holding their first debate Monday, with centrist Emmanuel Macron and far-right leader Marine Le Pen leading polls, and jobs and security among voters' top concerns.
Mr Fillon, who has been blighted by scandal throughout his campaign, will be keen to shift the focus from his alleged misuse of public funds to his manifesto pledges.
Macron will go on to beat Le Pen with 63 percent to 37 percent in the second round, according to Elabe.
In a taste of what awaits Macron on Monday, Hamon laid in to the former Rothschild banker, casting him as the candidate of the elite.
The election could hinge on turnout, after several political veterans have already been sent packing by voters fed up with politics as usual.
His predicted runoff with Le Pen will be the most surprising since 2002 when the FN leader's father Jean-Marie Le Pen rocked the political establishment by getting into the second round in 2002 where he eventually lost to conservative Jacques Chirac.