By Michel Rose
MARSEILLE, France (Reuters) - President Emmanuel Macron promised on Saturday to make France the "first great nation" to stop using oil, coal and gas as energy sources, in a pitch to young and green voters he fears could abstain in next week's election runoff.
In a rally in the Mediterranean city of Marseille, which voted massively for left-wing firebrand Jean-Luc Melenchon in the first round of voting, Macron sought to widen what opinion polls show as a small lead over his far-right rival Marine Le Pen.
Ahead of the April 24 runoff, the presidential race is being fought on the left, with both contenders seeking to attract voters who chose Melenchon in the first round last Sunday.
Macron said he would put his next prime minister directly in charge of what he called "green planning", appealing to left-wing voters' nostalgia for post-war Communist-inspired central planning while tapping into 21st century worries about climate change.
"I have heard the anxiety amongst our young people," Macron told flag-waving supporters at a park overlooking the Old Port in Marseille, France's second city.
"This prime minister's mission will be to make France the first great nation to exit gas, oil and coal. It's possible, and we'll do it," Macron said. "Between coal and gas on one hand, and nuclear on the other, I choose nuclear."
The president wants to build six new nuclear reactors and launch studies for another eight, increase solar energy capacity tenfold and build 50 wind farms at sea by mid-century. He also wants to insulate 700,000 homes per year to save energy.
Macron, a centrist, also said he wanted to create a national day of nature in May every year. He slammed Le Pen as a "climate sceptic".
Melenchon came third on April 10 with more than 21% of the vote and as both runoff candidates seek to attract his supporters, Le Pen is going for the more working-class, rural part of that electorate by focusing on the cost of living, rising food costs and high petrol prices following the war in Ukraine.
Macron, meanwhile, is trying to woo the more educated, centre-left and urban segments of Melenchon supporters.
An opinion poll for Ipsos on Saturday showed 33% of Melenchon's voters planned to vote for Macron, 16% for Le Pen and 51% were undecided.
Thousands of anti-far right protesters marched across the country on Saturday as opponents of Le Pen seek to form a united front to prevent her from winning the runoff.
In Marseille, Mehdi Sam, a 25-year old IT engineer and left-wing voter said he found Macron's programme on the environment interesting, but added that his father, who voted Melenchon in the first round, was planning to abstain in the runoff.
"I think that's a mistake. I can understand that not everything suits him (in Macron) ... but we forget what's on the other side: a camp that's extreme, with very negative values, and that's not the France I want for tomorrow," he said.