PARIS (Reuters) - France’s popular former economy minister, Emmanuel Macron, styling himself the workers’ champion, drew 15,000 supporters to a rally in Paris on Saturday which reinforced his image as the dark horse in the race for the Elysee.

Emmanuel Macron, head of the political movement "En Marche" or "Forward" and candidate for the 2017 French presidential election, attends an economic forum in Paris, France, December 1, 2016. REUTERS/Jacky Naegelen

The 38-year-old Macron, once a protege of President Francois Hollande, staged what his supporters called a “tour de force” at the rally, brushing off criticism by his erstwhile Socialist allies for running as an independent in the 2017 election.

Macron has refused pleas - most recently by former prime minister Manuel Valls who is seeking the Socialist party ticket - to join in the Left’s attempts to decide on a single candidate for next spring’s election.

He signaled on Saturday he would not change his mind.

The former investment banker pledged to cut taxes on workers and employers, while raising taxes on income from investments and wealthy pensioners.

“I ask them, in all transparency, for this little effort of a few euros per month because the country’s workers need it ... I am the workers’ candidate,” he declared to cheers.

The large turnout on a cold evening eclipsed last weekend’s modest gathering by the Socialists when party grandees struggled to reenergize the Left’s faithful at a convention that drew only 2,500 supporters.

Polls show there is little chance of any left-wing candidate reaching the election run-off next May and, barring an upset, the stage seems set for a head-to-head between conservative Francois Fillon and far-right leader Marine Le Pen.

Fillon, a center-right former prime minister who has pledged to cut deep into the public sector, would easily beat the anti-immigrant and anti-euro Le Pen, taking two thirds of the vote if the polls are correct.

But, with his pledge of being “neither on the left nor on the right”, Macron is a wild card in the election that will be fought on high unemployment, national security and immigration.

His appeal for the support of the blue-collar worker on Saturday indicated he was out to upstage both the traditional Left as well as try to eat into the support base of the National Front’s Le Pen.

Aware of his need to convince left-wing voters sometimes wary of his pro-business stance, Macron slammed Fillon’s proposals to cut spending on public healthcare.

“It’s an attack on the middle class,” he said.

Macron quit as economy minister in the Valls government after he set up his own political movement called “En Marche”, which translates as “Forward” or “Onwards”.

Some say however he could fragment the Left’s electorate and enhance Le Pen’s chances of reaching the runoff next May. Supporters countered on Saturday by calling on others on the left, including Valls, to rally behind Macron.

“Who else can gather that many people these days?,” Lyon mayor Gerard Collomb, a Socialist party veteran and Macron supporter told reporters.

Opinion polls put Macron consistently ahead of Socialist candidates such as Valls who will compete for the party ticket in two-stage primaries in late January.

Macron has toned down his previous criticism of Socialist sacred cows, which had rattled left-wing sympathizers but made him increasingly popular with the wider electorate.

On the 35-hour work-week, he said he would let unions and employers reach deals to opt out of it, rather than raising the legal limit to 39 hours as Fillon advocates.