France election 2017: Marine Le Pen, Emmanuel Macron face opposition on fractious May 1

France's rivals for the presidency, centrist frontrunner Emmanuel Macron and far-right rival Marine Le Pen, braced for major shows of opposition to their programmes on Monday on a fractious May 1 holiday.

Both candidates will hold rallies just six days before the decisive second round. France's powerful unions will also stage traditional May Day marches but the demonstrations will underscore the conspicuous absence of the united front they showed in 2002 when Le Pen's father Jean-Marie shocked the country by reaching the run-off.

On this day 15 years ago, some 1.3 million people took to the streets of France in union-led demonstrations to protest against the founder of the National Front (FN), including 400,000 in Paris. That show of force, coupled with a political closing of ranks, helped centre-right Jacques Chirac inflict a crushing defeat on Le Pen senior.

This time, unions are divided over the choice between his 48-year-old daughter and 39-year-old Macron. Two, the CFDT and Unsa, have called for their members to back Macron on Sunday. But while three other more left-wing unions including the biggest, the CGT, have called for a demonstration against Marine Le Pen's vision of French identity and opposition to immigration, they have stopped short of backing Macron.

For many on the left, the former banker's outlook is too economically liberal. Le Pen has tried to capitalise on their fears, recently saying that Macron would turn France into "a space, a wasteland, a trading room where there are only consumers and producers."

Some militants have formed a movement they have called "Social Front" to block both candidates and will march on Monday under a banner saying: "Rock and a hard place: Social Front, it will be won in the streets."

CGT leader Philippe Martinez said he "deeply disagreed" with that approach, arguing that Le Pen and Macron "are not the same thing".

"The National Front is a racist, xenophobic party that is anti-women and anti-workers because it is also an economically liberal party," he said.

Le Pen hit back that the unions "are not defending workers' interests, they are looking after their own interests".

"To see the CGT call on its members to vote for Macron, who is going to weaken the workers' lot... is just astonishing," she said. Macron is currently favourite to become France's youngest ever president, leading Le Pen by 19 points in the polls, but she has shown she is a canny campaigner.