Greece’s ruling Syriza party is sliding toward a split as hard-left dissidents resist Greek Premier Alexis Tsipras’s acquiescence to creditors’ demands, endangering his fragile government and complicating the country’s ongoing bailout negotiations, according to the Wall Street Journal.

Syriza’s central committee—the body that sets the party’s policies—is due to meet Thursday to decide how to handle a rift that erupted in mid-July, when a quarter of the party’s lawmakers voted against a set of austerity measures, which were a prerequisite for the country’s prospective new bailout program from the eurozone and International Monetary Fund, worth up to €86 billion ($95 billion).

The central committee is due to decide whether Syriza will hold an emergency congress in September or carry out an inner-party referendum to decide on the party’s future.

If the committee decides to hold a referendum, it could take place this weekend.

Despite his consistently high popularity with the Greek public, Mr. Tsipras faces a difficult battle inside his own party with an uncertain outcome.

After a tentative deal on July 12 between eurozone leaders, more than half of the Syriza central committee’s members signed a statement denouncing the agreement and calling it a “coup” against Greece.

Mr. Tsipras and his top aides have said the government aims to finalize a bailout deal as quickly as possible, before dealing with Syriza’s internal rebels at a party congress in the fall, which could lead to the party splitting, with national elections following soon afterward.

“Syriza’s problems are not going to become the country’s problems,” Mr. Tsipras said in an interview Wednesday on local radio.

Mr. Tsipras said he expects all party members to support the government’s efforts until after the deal is sealed and the country has escaped the danger of bankruptcy before setting in motion any inner-party changes.