BELGRADE, Serbia — Serbian President Aleksandar Vucic and his populist right-wing party appeared headed to victory in Sunday’s national election, extending a decade-long authoritarian rule in the Balkan country, according to early pollsters’ projections.

The IPSOS and CESID pollsters, which have proven reliable in previous Serbian ballots, predicted Vucic would end up with nearly 60% of the votes. If confirmed in the official tally, Vucic would win outright a second five-year term as president and a runoff vote would not be needed.

Vucic later declared victory in both the presidential and parliamentary vote, saying he was proud to win the second outright mandate without going into a runoff.

“I huge thank you to the citizens of Serbia,” he said, quoting similar results. “I’m endlessly proud and endlessly happy.”

The pollsters projected that Vucic’s Serbian Progressive Party would win the most votes in the parliamentary ballot, with around 43%, followed by the United for Victory of Serbia opposition group with around 13%.

Serbia’s state election authorities said they would not make any official announcements on the vote count before Monday. The unprecedented move by the commission was branded as scandalous by opposition officials who said that it allowed Vucic to take over the state institution by giving him priority in announcing the official results.

Opposition claims of widespread irregularities marked the election Sunday. The governing populists have denied vote manipulation and pressure on voters.

Some 6.5 million voters were eligible to choose the president and a new parliament, and elections were being held as well for local authorities in the capital, Belgrade, and in over a dozen other towns and municipalities. Turnout was reported about 55% an hour before polls closed, higher than in most Serbian elections.

Opposition groups still stood a chance of winning in Belgrade, analysts said, which would deal a serious blow to Vucic’s autocratic rule. The governing party is less popular in the capital due partly to a number of corruption-plagued construction projects that have devastated Belgrade’s urban core.

“These elections are the beginning of the end of Aleksandar Vucic,” said Zdravko Ponos of the United for Victory of Serbia coalition who was running second in the presidential vote. “These elections triggered hope and we cannot betray that hope.”

Ponos, a Western-educated former army chief of staff, had hoped to push Vucic into a second round in the presidential ballot.

Opposition groups said multiple irregularities were spotted during the voting. Opposition election controllers reported widespread ghost voting — voting under the names of people who are dead or don’t exist — as well ruling party activists offering money in exchange for votes.

One opposition leader was attacked outside Vucic’s party offices in a Belgrade suburb, suffering facial injuries. A ruling party official was reportedly attacked in the central town of Nis.

Vucic, a former ultranationalist who has boasted of his close ties with Russian President Vladimir Putin, has sought to portray himself as a guarantor of stability amid the turmoil raging in Europe due to Russia’s invasion of Ukraine.

In a country that went through a series of wars in the 1990s and a NATO bombing in 1999, fears of a conflict spilling over have played into Vucic’s hands. Although Serbia is formally seeking entry into the 27-nation European Union, Vucic has fostered close ties with Russia and China, counting on the Serbs’ resentment of the West over the 1999 NATO air war.

Serbia has supported a U.N. resolution that condemned the Russian invasion of Ukraine, but Belgrade has not joined Western sanctions against Moscow, a historic Slavic ally.

Vucic said the Ukrainian crisis influenced hugely the election in Serbia, shifting the already predominantly right-leaning nation further to the right. He said that after the election “Serbia will have to determine what it will do in the future.”

Beleaguered opposition groups mostly refrained from publicly advocating a tougher line on Moscow. Russia has supported Serbia’s claim to Kosovo, a former province that declared Western-backed independence in 2008.