Marine Le Pen's niece Marion Marechal, a popular figure among far-right French voters, on Friday said Eric Zemmour was a better presidential candidate, piling woes onto a campaign already troubled by the defection of two EU lawmakers.
Le Pen ranks second or third in opinion polls that show a tussle among right and far-right candidates to win a second-round runoff spot against President Emmanuel Macron in the April elections. Macron himself is leading polls and seen as likely to secure the other spot.
Marechal, a 32-year old former lawmaker, told Le Parisien and Le Figaro in separate interviews that she considers her aunt's far-right rival Zemmour had adopted a better strategy, even though he is currently running fourth in opinion polls.
"Unlike Marine Le Pen Zemmour still has ample room to rise further (in polls)," Marechal told Le Figaro newspaper.
She said that because he was new to politics and was seeking to bridge gaps between parties, Zemmour was better placed to get wide-ranging support than Le Pen's party, which other parties, including on the mainstream right, often shun.
Her comments went to the heart of a debate that could re-define France's right and far-right for years to come.
Marechal, once a rising star in the Le Pen family's National Rally party, quit politics five years ago.
She said on Friday she wanted to return but hadn't quite decided yet whether to rally with Zemmour's campaign for fear it would revive feuds that had torn the Le Pen family and the party apart for years.
But the divisions she said she wanted to avoid creating were immediately clear with her aunt's reaction.
"It's brutal, it's violent, it's tough for me," a visibly moved Le Pen told CNews, adding it was "painful" on a person level and "incomprehensible" politically.
The 53-year-old veteran politician noted that polls showed her and not Zemmour as likely to reach the second round in April, in a repeat of the 2017 match that Macron won.
While the National Front - rebranded National Rally - has dominated the French far-right for decades, first led by Le Pen's father Jean-Marie and then by her since 2011, it has always failed to reach power beyond a few municipalities.
(Reporting by Sophie Louet and Ingrid Melander; Editing by Frances Kerry)