Constitutional Court says Zoran Milanovic cannot take up PM post because he did not first step down as president.
Featured Content
The country is likely to face a period of uncertainty as HDZ negotiates with smaller parties to form a government.
Exit polls expected minutes after voting ends at 7pm (17:00 GMT), with official results due in the coming days.
Bus carrying some 40 passengers veered off elevated overpass, plunged about 15 metres and caught fire, officials report.