By Michel Rose

PARIS (Reuters) -The Greens candidate on Monday pulled out of a run-off election in southeastern France set for next Sunday, making it harder for far-right leader Marine Le Pen’s party to beat the centre-right and take control of the region.

Le Pen is hoping to win the Provence-Alpes-Cote d’Azur region in the elections for the regional parliament and president, gaining a platform and political momentum for her planned bid for the French presidency in the 2022 election.

Her candidate, Thierry Mariani, came in just ahead of the centre-right alliance led by incumbent Renaud Muselier in Sunday’s first round, a narrower margin than expected in what is her best chance of winning a region for the first time ever.

French mainstream parties have traditionally rallied behind the one best placed to keep the far right out of power in local and national elections, a strategy known as “le front republicain”.

But on Sunday night, the Green candidate in the southeast, Jean-Laurent Felizia, initially refused to pull out, drawing condemnation from swathes of the French political class.

Under pressure, Felizia eventually announced he had dropped his bid to stay in the race in order to deprive Le Pen of “a stepping stone for her sinister ambitions”.

“I cannot play with fire, for the sake of our children, our grandchildren,” Felizia said.

Le Pen was quick to react, denouncing in a tweet what she called the betrayal and hypocrisy of “the system” and urging voters to get out and vote in Sunday’s run-off.

One opinion poll last week suggested the far right could still win Provence even if all parties do rally behind the incumbent.

Le Pen has made a concerted push to detoxify her party’s image and erode the mainstream right’s vote with a less inflammatory brand of eurosceptic, anti-immigration populist politics.

Elsewhere in Sunday’s regional elections across France, left-wing candidates in the greater Paris region agreed to present a single ticket to increase their chances of ousting the centre-right incumbent, Valerie Pecresse.

Pecresse is tipped as a possible conservative candidate to run in the 2022 presidential election, when President Emmanuel Macron hopes to win a second five-year term.

Macron’s LREM party finished fifth nationwide in the first round of Sunday’s regional vote – as badly as expected, amid discontent over crime, threats to jobs from globalisation and a ruling elite seen as out of touch with ordinary citizens.

(Editing by Mark Heinrich and Gareth Jones)