Croatia's incumbent President Zoran Milanovic, supported by the Social Democratic Party (SDP), fell just short of winning in the first round of presidential elections on Sunday despite leading his closest rival by around 30 percentage points.

According to unofficial results announced by the State Electoral Commission (DIP), 99.67 percent of the votes have been counted.

Although exit polls initially showed Milanovic with more than 50 percent of the vote, the yet-to-be-finalized results indicate he secured 49.1 percent.

His opponent in the second round will be Dragan Primorac, the candidate of the ruling centre-right Croatian Democratic Union (HDZ) and former education minister, who received 19.4 percent of the vote.

While the SDP experienced both joy and disappointment, HDZ representatives acknowledged that they did not expect such a significant gap but emphasized that the second round represents a fresh start.

If the results are confirmed, Milanovic and Primorac will face off in a run-off on January 12.