Jean-Luc Melenchon, the fiery leftist whose anti-capitalist agenda has shaken up France's presidential race, has gained four points in two weeks in the polls, a result that would see him seize third place in the first-round vote.
A poll for LH2/Yahoo published on Sunday showed that his more mainstream Socialist rival Francois Hollande would still win the first-round vote on April 22 with 28.5 percent.
Hollande lost two points since a poll published on March 18, but is still ahead of President Nicolas Sarkozy, whose campaign was boosted in the aftermath of a killing spree by an Islamist gunman. The poll gave Sarkozy 27.5 percent, which was unchanged.
But it was the result for Melenchon, who on Sunday took his campaign to a poor Parisian suburb, that suggested his radical left-wing rhetoric and attempts to push Hollande's agenda further to the left are paying off.
Melenchon, the co-head of a group of far-left parties, would win 15 percent of the first-round vote, the poll showed, pushing past far-right candidate Marine Le Pen, who was at 13.5 percent.
Critics have accused Melenchon of drawing supporters away from Hollande and diluting the cohesion of the Left.
At the same time, Melenchon's possible eclipse of Le Pen - a charismatic orator with a flair for populist rhetoric - can be seen as a threat to Sarkozy, who would need the support of her right-wing voters in order to clinch the second round.
At least one other survey in the last two weeks has also put Melenchon third, underscoring the momentum enjoyed by the one-time Trotskyist who surprised many by surpassing the symbolic 10 percent mark in the polls for the first round in mid-March.
Melenchon on Sunday addressed several thousand people at a stadium south of Paris in Grigny, a low-income dormitory suburb.
Don't allow your neighbourhoods, your suburbs to be a political desert, Melenchon told the crowd.
While the issue of suburban ghettos has not been a focus of this race, the killing of seven people last month by a gunman from one such urban enclave in the city of Toulouse highlighted the sense of exclusion felt in these areas that are home to many immigrants.
INFLUENCE ON OTHER CANDIDATES
For the May 6 second round vote, the survey gave Hollande 54 percent versus 46 percent for Sarkozy. Hollande lost one point since March 18, while Sarkozy gained one.
Melenchon's no-holds-barred style has forced Hollande and even Sarkozy to make more overtures to workers, including promises to control executive pay and severance packages.
In his most dramatic move, Hollande announced a plan to tax those earning over 1 million euros at a 75 percent annual rate.
Conservative voters worry that a strong first-round performance by Melenchon could mean more legislative seats in June for the far-Left, which is allied with the Communists.
On Sunday, the head of France's principal business lobby MEDEF, Laurence Parisot, told iTele she considered Melenchon divisive and his rhetoric objectionable.
I find Melenchon is much more the inheritor of The Terror, rather than of the finest values of the Revolution, said Parisot, citing the bloody period after the French Revolution when tens of thousands were beheaded at the guillotine.
Earlier this month, Melenchon held a mass rally at Paris' Bastille plaza, the former prison destroyed by the mob during the Revolution. He attracted tens of thousands of supporters who listened to his call for a citizens' insurrection.
The LH2/Yahoo telephone survey of 973 people was conducted on March 30-31. The margin of error for the first round was +/- 3.5 points, with +/- 4 points for the second.
(Additional Reporting By Chine Labbe; Editing by Andrew Osborn)