By Brian Love and Jean-Paul PELISSIER
PARIS/LE GRAU DU ROI, France (Reuters) - France's presidential candidates battled for the popular vote on Thursday with far-right Marine Le Pen wooing fishermen and Emmanuel Macron playing soccer as polls showed the centrist's commanding lead narrow marginally.
As runner-up in last Sunday's opening ballot, Le Pen remained the underdog, but several polls suggested she had made a more impressive start to the last lap of campaigning than Macron.
A daily Opinionway poll saw Macron's predicted score dipping to 59 percent for the first time since mid-March.
Election graphic: http://tmsnrt.rs/2p6zUPE
First round election graphic: http://tmsnrt.rs/2lPduBG
A Harris survey showed Macron garnering 61 percent of voting intentions, but suggested momentum was on Le Pen's side as the centrist's lead narrowed by several percentage points.
Dressed in fishermen's yellow oilskins, Le Pen, 48, grappled with a freshly caught octopus on a fishing boat out at sea first thing on Thursday. She told reporters on the quayside she would defend seafarers and all endangered sectors against invasive EU regulations.
"Let me warn you, that man (Macron) will destroy our entire social and economic structure," she told a horde of journalists at Le Grau du Roi, a port west of Marseille.
Macron, a 39-year-old who did a stint as economy minister in the outgoing Socialist government before breaking away to launch his own political movement, mocked her photo opportunity.
"Madame Le Pen has gone fishing. Enjoy the outing. The exit from Europe that she is proposing will spell the end of French fisheries," he tweeted.
Macron took his campaign to Sarcelles, a poor Parisian suburb with a large community of North African and sub-Saharan African descent where more than one in three young people are out of work, double the national average.
In stark contrast to Wednesday, when he was heckled by factory workers in northern France, the ex-banker was greeted to cheers and kicked a football around with youngsters.
He hit back at Le Pen's attempts to portray herself as the woman of the people, accusing the trained lawyer, who was born and raised in a wealthy Paris suburb, of hypocrisy, making false promises and continuing the "xenophobic" policies of her father Jean-Marie Le Pen.
"She is lying to you," Macron said in the town, where the majority voted for the far-left in last week's first round.
"France is not the vicious and repressive face that Mrs Le Pen carries. I will not let her trivialize what the National Front is, which is a xenophobic party."
Both contenders redoubled their attempts to paint the other as the candidate of the political establishment on Thursday and appealed for support from across the political spectrum after an election race that has alienated some voters.
As the final vote on May 7 approaches, the candidates have plenty of scope - but little time - to pick up support. In the first round, they won less than half of the votes between them and have fewer than 10 days to convince the other 55 percent.
Macron, decrying Le Pen as a "political heiress" and defending his experience in the private sector as a banker, urged people who had backed rivals such as conservative Francois Fillon or leftist Jean-Luc Melenchon to give him a chance.
"I will not consider a vote in my favor as a blank cheque," Macron told French television on Thursday night.
Eurosceptic Le Pen - simultaneously holding a rally in the southern city of Nice, where she described Macron as a "product of the system" - also sought to lure potential Fillon voters as she struck a more conciliatory tone on the European Union.
She said she wanted to replace the "grey" EU with a "happy" one and omitted any mention of her anti-euro stance.
But she also pressed home her central message on putting the brakes on immigration and reinstating border checks in France, asking the 3,000 strong-crowd: "Mass immigration - more, or stop?" and drawing chants of "Stop!" from supporters.
One group that will be key is the 20 percent who chose far-left candidate Melenchon in the first round of voting on April 23.
Unlike the other main candidates who said they would vote for Macron to block the far-right, Melenchon has declined to give his view. His campaign has instead launched a survey of its members to see if they will vote for Macron or abstain, though voting for Le Pen is not an option.
Melenchon's "France Unbowed" movement had a similar anti-globalization, pro-worker protection message to Le Pen's, but is sharply opposed to her position that immigration and radical Islam are at the roots of France's problems.
In Paris and the western city of Rennes on Thursday, riot police clashed with youths demonstrating against both candidates. Students have been holding "neither Le Pen, nor Macron" protests at high schools since Sunday's vote.
In an interview with Reuters, Christian Estrosi, the right-wing president of the southeastern region, said it was a mistake to take Le Pen's victory chances lightly.
"She can win. In my political family, some are wrong to neglect the risk and not to take the second round more seriously," he said.
Former Socialist Prime Minister Manuel Valls also echoed that message, telling BFM TV that Le Pen could win if people did not unite behind Macron.
Campaigning took a spectacular turn on Wednesday when Le Pen paid a surprise visit to a doomed Whirlpool appliance plant in her opponent's home town and promised to save it, just as Macron was meeting labor representatives behind closed doors nearby.
Macron later went to the site himself and, although he held his ground and the tension eventually eased, television channels repeatedly broadcast footage of him being heckled.
(Reporting by Leigh Thomas, Matthias Blamont, Emmanuel Jarry, and Ingrid Melander in Nice; Writing by John Irish and Sarah White; Editing by Tom Heneghan and Andrew Hay)