TUNIS — Rival ambitions, insults and accusations of violence have brought Tunisia’s ruling party to the brink of collapse as the country struggles to lead the way towards a post-Arab Spring democracy.

The secularist Nidaa Tounes party was already weakened by the departure of its leader Beji Caid Essebsi, in line with the constitution after he was elected president last December.

It has now been riven for months by bad blood between its secretary general, Mohsen Marzouk, and the president’s son Hafedh Caid Essebsi, in what insiders are calling a “battle for succession”.

The rivalry threatens to tear apart the government in a country held up as a rare success story for the Arab Spring after its 2011 overthrow of longtime dictator Zine El Abidine Ben Ali.

On Sunday, the bitterness reached new heights with alleged violence during a meeting of Nidaa’s executive committee in Hammamet.

Footage widely shared on the Internet shows a group of people armed with sticks — allegedly Essebsi supporters — blocking the entrance to the venue and hitting people trying to enter.

Several pro-Marzouk committee members charged that this amounted to “fascist aggression” orchestrated by “certain leaders of the party” intent on seizing control of it.

As a loose alliance of leftist and centre-right figures, together with former officials of Ben Ali’s regime, Nidaa Tounes has survived past internal crises.

But a key party congress has been delayed for several months, as protests are voiced over the ambitions of the 88-year-old president’s son, who is in his early 50s.

Resigning last month from his post as minister in charge of relations with parliament, party member Lazhar Akremi warned that the president may be trying to set up a dynasty.

“We’ve said no to hereditary power, no to the return of the old regime,” he said at the time.