Unofficial vote tallies show Croatia's conservative opposition Croatian Democratic Union (HDZ) winning about 60 seats in Sunday's parliamentary polls, with the ruling Social Democrats carrying 53.
With 50 percent of the ballots tallied early Monday, a new party called "Most" was running third with a projected 19 seats in the 151-member legislature. That party appeared poised to play a crucial role in upcoming talks to form a new government.
Conservatives led by former intelligence chief Tomislav Karamarko campaigned on a platform highly critical the government of center-left Prime Minister Zoran Milanovic for allowing hundreds of thousands of mostly Middle Eastern migrants free passage through the country in recent months.
Karamarko, whose nationalist-minded followers guided Croatia to independence from the Serb-dominated former Yugoslav federation, also used his campaign to highlight patriotism and promise new jobs in the mainly Roman catholic nation of 4.4 million people.
But his party was voted out of power in 2011, following a series of high profile scandals involving then-prime minister Ivo Sanader.
Milanovic's ruling coalition campaigned on the promise of steady economic growth, while repeatedly attempting to tie the opposition to corruption.
Analysts say Milanovic's pre-election attempts to balance compassion for migrants with promises to defend national interests satisfied many voters who were forced to flee fighting in the 1990s during the Balkan wars.