Jean-Marie Le Pen is facing expulsion from the far-right party he founded due to a deepening rift with his daughter and party's current leader Marine Le Pen over anti-Semitic remarks.
Marine said she will actively oppose the 86-year-old firebrand's candidacy with France's Front National (FN) in upcoming regional elections, after he repeated claims that Nazi gas chambers were a "detail in history".
Referring to her father by his full name in a party statement, Marine said he "seems to have entered a downward spiral between a scorched earth strategy and political suicide".
"Given this situation, I have informed Jean-Marie Le Pen that I will oppose... his candidacy in Provence-Alpes-Cote d'Azur," she said.
"His status as honorary president does not allow him to take the National Front hostage to such gross provocations which seem aimed at hurting me but, unfortunately, are a heavy blow to the whole movement," Marine wrote in what was her first all-out attack on her father since she took the reins of the party from him in 2011.
She was backed by other party officials, with FN deputy presidents Florian Philippot and Louis Aliot tweeting of a "definitive and total political rupture" with the elderly leader because of his "anti-Semitic rubbish".
Others called for Jean-Marie, who founded FN in 1972, to resign as honorary president.
Mother-of-three Marine had previously distance herself from her father's racist and anti-Semitic views, as she worked to turn FN from fringe extremist party to mainstream political force.
Her so-called de-demonization process has been largely successful, with FN now polling at around 25% nationwide.
As part of the clean-up, Jean-Marie -- who has received regular fines for inciting racial hatred during his decades-long political career -- was gagged and pushed to the margins.
In June, his blog was dropped from the FN official website after he used the platform to lambaste one of his more vocal critics, Jewish singer Patrick Bruel, saying: "We'll do an oven load next time."
The final straw, however, came in a radio interview in which he defended the head of France's collaborationist government of Vichy, Marshal Petain, and repeated claims that gas chambers used to kill Jews in Nazi concentration camps were "merely a detail in the history of the second world war".
In 1991, Jean-Marie was famously ordered to pay €183,000 (£135,000, $207,000) for saying the same thing.
Marine has now called a meeting of FN's executive committee to discuss further possible disciplinary measures against him, amid media speculation he might me expelled.
Marine's niece, lawmaker Marion Maréchal-Le Pen, 25, has been widely tipped as replacement for the leading candidate role in the Provence-Alpes-Cote d'Azur in polls later this year.