Updated

The Latest on Serbia's presidential election (all times local):

3:35 p.m.

About 30 percent of Serbia's electorate had turned out to vote in the country's presidential election six hours before the polls were to close.

That turnout is about the same as when Prime Minister Aleksander Vucic's right-wing party won a parliamentary vote in 2014. Vucic is now seeking the presidency.

Opposition candidates were expected to benefit from a higher turnout.

Vucic needs to win by more than 50 percent of the vote to avoid a runoff election on April 16 that would put him in a much trickier position against a single opposition candidate.

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11:55 a.m.

Prime Minister Aleksander Vucic's main challengers in the presidential election include human-rights lawyer and former Ombudsman Sasa Jankovic, former Foreign Minister Vuk Jeremic and Vucic's former mentor, Vojislav Seselj.

Jankovic, an independent candidate, said Sunday he's happy with his campaign, which has galvanized the pro-democratic movement in Serbia that has been upset with the country's persistent corruption and growing autocracy.

The opposition has accused Vucic of muzzling the media and intimidating voters ahead of the election. Vucic denies such accusations, saying only he can bring stability to a region scarred by the wars of the 1990s, which Vucic had supported at the time.

One of the biggest surprises of the election campaign has been Luka Maksimovic, a media student who is running as a parody politician.

Decked out in a white suit, oversized jewelry and a man-bun, Maksimovic's satirical candidate mocks corruption in Serbian politics by promising to steal if he is elected.

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9:45 a.m.

Serbian Prime Minister Aleksander Vucic is taking inspiration from Russian President Vladimir Putin.

If he wins the country's presidential election as expected Sunday, Vucic is likely to transform the Serbia's largely ceremonial presidency into a more powerful position that would let him rule unchallenged, like Putin has.

Contrary to his claims that he wants to lead Serbia into the EU, Vucic has been pushing for deeper ties with longtime ally Russia.

Putin has endorsed Vucic in the election against 10 opposition candidates.

Right before the vote, Vucic visited Putin, who reportedly promised to deliver fighter planes, battle tanks and armored vehicles to Serbia.

The move triggered fears of an arms race in the western Balkans, which Russia considers its sphere of influence.

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8:45 a.m.

Voters in Serbia are casting ballots in a presidential election seen as a test of public support for populist Prime Minister Aleksandar Vucic and his autocratic rule.

Vucic, an ultranationalist turned a pro-EU politician, is slated to win by a high margin against 10 opposition candidates. His political clout could face a blow, however, if he does not sweep his opponents in the first round of voting Sunday.

Vucic needs to win by more than 50 percent of the vote to avoid a runoff election on April 16 that would put him in a much trickier position against a single opposition candidate.

Vucic, prime minister since 2014, is expected to use his win to appoint a figurehead successor and transform the presidency from a ceremonial office into a more muscular role.