PARIS France's far-right National Front party celebrated a fourfold increase in requests for membership on Thursday as a feud convulsed its main right-wing rival the UMP.
UMP leadership contenders accuse one another of fraud in an internal election and the party now risks a permanent split just months after it lost power, a potential gift for Socialist President Francois Hollande.
An opinion poll showed the anti-immigration National Front, which opposes the euro currency, could be an even bigger winner from the infighting.
What started as a dry affair that fascinated few beyond UMP ranks has become a daily soap opera that is making the party the object of ridicule.
"This is the funniest comedy of the year," movie director Luc Besson told a French newspaper. "Nobody would even dare write that for TV or cinema."
Right-wing daily Le Figaro called the squabbling "live suicide" on its front page this week and National Front leaders drew mocking parallels with the U.S. TV soap opera Dallas.
Marion Marechal-Le Pen, niece of National Front boss Marine Le Pen, said her party had enrolled 600 members a day over the past week, compared to around 150 per day previously. Many could have come from the UMP, she told LCI television.
The opinion poll published on Thursday made grim reading for the party that ruled Europe's second-biggest economy for a decade until Hollande defeated incumbent Nicolas Sarkozy in a May presidential election run-off.
Some 38 percent of respondents felt the National Front would be the biggest beneficiary of the UMP's squabbling, well ahead of Hollande's Socialists.
There is little sign that the acrimony will end soon, with leadership candidate Francois Fillon refusing to accept defeat to his rival Jean-Francois Cope in a recount that followed the disputed initial vote on November 18.
Cope is a disciple of Sarkozy with hardline views on immigration and religion. Fillon was a popular prime minister under Sarkozy and strikes a more urbane, reserved image.
Sarkozy, who led the UMP before his 2007-2012 presidential term, is "furious" over the infighting, according to long-time friends, and returned from semi-retirement this week to broker a truce.
The deal fell apart the morning after it was struck.
Marine Le Pen scored nearly 18 percent of the vote in the first round of the presidential vote and Marion, granddaughter of party founder Jean-Marie Le Pen, became the first National Front member of the National Assembly since the mid-1980s.
They hope the economic crisis plaguing Europe and cutbacks planned to reduce a bloated state debt will push more poor and disenchanted voters their way and help the National Front gain ground in local elections set for 2014 and 2015.
Fillon has created a splinter group in the UMP called R-UMP (Rassemblement UMP). It was soon the butt of jokes on TV shows and Twitter because of the acronym's meaning in English.
A UMP member of parliament, Damien Meslot, is now calling for a grassroots revolt against "thirty madmen" at UMP headquarters in Paris.
Cope and Fillon have agreed to Sarkozy's latest request to hold a new election, but only if an internal referendum is held first to see if party members support yet another vote.
Another group is suggesting that a committee be set up to assess the merits of a referendum and a new election. Meslot proposes that UMP regional federations hold votes among 300,000 members to decide whether to hold another re-run.
(Reporting By Brian Love; Editing by Tom Pfeiffer)