The leadership of the Social Democratic Party (SDP) meets on Thursday to start the procedure for a party election, and the party is expected to choose a new leader by the end of November or no later than mid-December.
The party's main committee is expected to convene on Saturday to set a date for the leadership election, after Zoran Milanovic said on Monday that he would not seek another term as leader following the SDP's failure at Sunday's snap parliamentary election.
The SDP's current member of the European Parliament Tonino Picula and former interior minister Ranko Ostojic have announced their candidacies for the top position in the party.
The name of former transport minister Sinisa Hajdas Doncic has also been mentioned in this context, but sources in the SDP have told Hina that he will probably not run and that Milanovic's close associates will back Ostojic.
Zvonimir Mrsic, another possible candidate, denied via social networks on Tuesday that he would run for leadership, saying that his ambitions were tied to the Podravka food company, where he serves as chairman of the managing board.
Primorje-Gorski Kotar County head Zlatko Komadina, whom Milanovic defeated in the leadership race in April, was unavailable to comment on whether he intended to run for leadership once again or would support another candidate.
The head of the SDP's Zagreb branch, Davor Bernardic, is also a possible candidate, but in a statement to Hina he did not explicitly confirm whether he would stand in the leadership race or not.
In Sunday's early parliamentary election the SDP won 54 seats in the 151-seat parliament, while its main rival, the centre-right HDZ, captured 61 seats. SDP members are criticising their leader over the fact that the party has not won elections since 2011 and some of them believe that their latest defeat was down to Milanovic's tough rhetoric during the campaign.
Milanovic's critics claim that the SDP has lost over 300,000 votes since the 2011 election, citing considerably poorer results in the party's strongholds Rijeka and Zagreb.