PARIS (AFP) - France on Saturday (April 23) prepared to choose between centrist President Emmanuel Macron and far-right challenger Marine Le Pen to rule the country for the next five years after a bitterly contested and polarising election campaign.

Mr Macron is the favourite to win re-election in the run-off ballot on Sunday, and there are indications he bolstered his advantage with a combative performance in the one-off election debate against a somewhat defensive Ms Le Pen.

But the President and his allies have insisted over the last week that nothing is in the bag, with a strong turnout crucial to avoid a shock in France comparable to the 2016 polls that led to Brexit in Britain and the rise to power of Mr Donald Trump in the United States.

A Le Pen victory would also send shockwaves across Europe. Left-wing European Union leaders including German Chancellor Olaf Scholz have pleaded with France to choose Mr Macron over his rival.

The stakes are huge - Ms Le Pen would become modern France's first far-right leader and first female president. Mr Macron would be the first French president to win re-election in two decades.

If elected, Mr Macron is expected, in a symbolic gesture, to address supporters on the Champ de Mars in central Paris at the foot of the Eiffel Tower.

Polls in mainland France will open at 0600 GMT (2pm Singapore time) on Sunday and close 12 hours later, immediately followed by projections that usually predict the result with a degree of accuracy.

But voters in French overseas territories that span the globe will start voting earlier Paris time, beginning with those in North America and the Caribbean on Saturday, followed by the Pacific and then the Indian Ocean.

'Woke up with hangover'

Saturday is marked by a campaign blackout, with no campaigning allowed and no more polls published.

Mr Macron and Ms Le Pen threw themselves into a final flurry of campaigning on Friday, firing off attacks in interviews before last-minute walkabouts and rallies.

Ms Le Pen insisted that opinion polls giving Mr Macron the lead would be proved wrong and took aim at her rival's plan to push back the retirement age from 62 to 65.

Mr Macron for his part said Ms Le Pen was trying to mask an authoritarian "extreme right" platform that stigmatises Muslims with a plan to outlaw headscarves in public.

Analysts say abstention rates could reach 25 per cent to 30 per cent, in particular among left-wing voters unhappy with Mr Macron's pro-business agenda, not least his tax cuts for businesses and the highest earners.

Spring school holidays will also be in full swing across much of the country this weekend, increasing the chances that many voters will not cast ballots.

Far-left leader Jean-Luc Melenchon, who scored a close third-place finish in the first-round vote on April 10, has refused to allow Mr Macron an easy ride by pointedly refusing to urge his millions of followers to back the President while insisting they must not cast a single vote for Ms Le Pen.

Polls have shown Mr Macron with a lead of some 10 percentage points. The highly anticipated TV debate did not change the trend and, if anything, allowed Mr Macron to open more of a gap.

The result is predicted to be closer than in 2017, when the same candidates faced off but Mr Macron carried the day with 66 per cent to 34 per cent.

In a final plea, Mr Macron urged voters not to repeat the mistake of those who opposed Brexit and the election of Mr Trump but decided to stay at home.

"They woke up the next day with a hangover," he told BFMTV. "We are going to decide the future of the country on April 24 and not the opinion polls on April 22."