Ex-president Nicolas Sarkozy on Monday waded in to a bitter leadership battle that has left France's main right-wing opposition party, the UMP, on the verge of collapse.
The UMP, the political heir to the party founded by Charles de Gaulle after World War II, was in turmoil after accusations of vote-rigging tarnished a leadership vote.
Still reeling from its loss of the presidency and parliament this year, the UMP is facing the spectre of an unprecedented split, with rivals Francois Fillon and Jean-Francois Cope refusing to back down in an increasingly angry dispute.
The ridicule foisted on the party over the leadership debacle has done serious damage to its image, benefitting Socialist President Francois Hollande as he struggles with a flat economy and and dropping popularity.
Some UMP deputies were already raising the prospect on Monday of breaking away from the party's parliamentary faction -- a move that would deprive it of crucial public funding.
Sarkozy met one of the rivals for the leadership, his former prime minister Fillon, for lunch after flying in early Monday from a conference in Shanghai.
The meeting lasted more than hour in Sarkozy's office in central Paris but there were no immediate signs of progress in the dispute.
A party heavyweight who earlier failed in a mediation bid had urged Sarkozy -- still enormously popular with the UMP rank-and-file despite his loss to Hollande in May's presidential vote -- to intervene.
"Clearly (Sarkozy) is the only one today to have enough authority to propose a way out," former foreign minister Alain Juppe told RTL radio.
Fillon, 58, and Cope, 48, have traded accusations of fraud and ballot-rigging since last Sunday's party election ended with Cope ahead a handful of votes.
A party appeals commission on Monday confirmed Cope's win, raising his margin of victory from 98 votes to nearly 1,000 following an examination of complaints over alleged irregularities.
Fillon's camp has accused the commission of pro-Cope bias and said he will pursue legal action, with one of his lawyers saying Monday that Fillon was preparing a civil suit to have the election results overturned.
Fillon's turning to the courts has raised the stakes in the dispute, with one senior UMP official calling it a "nuclear bomb" dropped on the party.
The UMP's opponents on both the left and far-right have watched with glee as the party implodes, with some already writing its obituary.
"The UMP no longer exists. The UMP is dead," Marine Le Pen, the leader of the far-right National Front, gloated on Monday.
Fillon was to bring together his supporters in parliament early Tuesday, with many clamouring to break away from the UMP if Cope remains leader.
Such a move would strip the UMP of the 42,000 euros in annual funding it receives for each of its members in the lower house National Assembly and upper house Senate.
Lawmakers have until Friday to declare their party affiliation for next year's funds.
The UMP has 183 members in France's 577-seat National Assembly, the second-largest group after the Socialists.
Polls show the overwhelming majority of French voters and UMP supporters would like to see the party run the election again, but Cope has rejected the idea.
Both men are fiscal conservatives advocating free-market policies and economic reforms, but Cope has carved out a niche on the right flank of the UMP with his tough-talking approach to immigration and Islam.