His strongest rival, independent candidate Josip Kregar, captured 22.98 per cent of votes.
In Croatia's second largest city, Split, independent candidate Zeljko Kerum was leading in the mayoral race with 40.42 per cent, according to results announced at Sunday midnight.
Kerum was followed by Ranko Ostojic, the candidate of the SDP, HSU, People's Party (HNS) and Democratic Centre (DC), with 36.64 per cent, according to returns from 130 out of a total of 162 polling stations.
For the first time mayors are elected by direct ballot. A candidate for a mayoral seat has to secure 50 percent of the vote in the first round. In case no candidate wins a majority, the first two candidates will compete in a runoff two weeks after the first round of voting.