With nearly 97% of the polling stations counted, Volodymyr Zelenskiy had 30% support in Sunday's vote, while President Petro Poroshenko was a distant second with just under 16% of the vote. Ex-Prime Minister Yulia Tymoshenko trailed behind in third with 13% support.
The strong showing for the 41-year-old Zelenskiy reflects the public longing for a fresh leader who has no links to Ukraine's corruption-ridden political elite and can offer a new approach to settling the grinding five-year conflict with Russia-backed separatists in eastern Ukraine that has left 13,000 dead since 2014.
"This is only the first step toward a great victory," Zelenskiy said. The top two candidates advance to a runoff on April 21. Final results are expected on Tuesday. Zelenskiy dismissed suggestions that he could pool forces with Tymoshenko to get her voters in the second round in exchange for forming a coalition later.
"We aren't making any deals with anyone," he said. "We are young people. We don't want to see all the past in our future." Like the character he plays in a TV comedy show, a schoolteacher-turned-president angry over corruption, Zelenskiy made fighting corruption a focus of his candidacy. He proposed a lifetime ban on holding public office for anyone convicted of graft. He also called for direct negotiations with Russia on ending the conflict in eastern Ukraine.
The election was marred by allegations of widespread vote buying. Police said they had received more than 2,100 complaints of violations on voting day alone in addition to hundreds of earlier voting fraud claims, including bribery attempts and removing ballots from polling stations.
Zelenskiy's headquarters alleged multiple voting and other cheating on the part of Poroshenko's campaign, but election officials said the vote took place without significant violations. Election monitors from the Organization for Security and Cooperation in Europe hailed Sunday's election as competitive and free, even though it criticized procedural violations and said there were indications that state resources were misused in the vote.
Poroshenko looked visibly relieved about surpassing Tymoshenko. "It's a tough lesson for me and my team," he said. "It's a reason for serious work to correct mistakes made over the past years." But Volodymyr Fesenko, head of the Penta Center Kiev-based independent think-tank, predicted that Zelenskiy will easily win the runoff.
"He doesn't even need to do anything, the current government already has done it, setting most voters against itself," Fesenko said. "Poroshenko needs to prepare for a defeat and try to seek security guarantees for himself and his team."
Poroshenko, 53, a confectionery tycoon before he was elected five years ago, saw his approval ratings sink amid Ukraine's economic woes and a sharp plunge in living standards. Poroshenko campaigned on promises to defeat the Russian-funded separatists in the east and to wrest back control of Crimea, the Black Sea peninsula that Russia annexed in 2014.
The OSCE said about 5 million people have been taking off Ukraine's voter registry as the government was unable to organize the presidential vote in Crimea or in the separatist-held east. In Moscow, Russian President Vladimir Putin's spokesman, Dmitry Peskov, refrained from commenting on Zelenskiy's strong performance, but indicated that the Kremlin would like to see a change of government.
"We would like to see not a party of war at the helm in Ukraine, but a party that aims at a gradual settlement in eastern Ukraine," he told reporters. A military embezzlement scheme that allegedly involved top Poroshenko associates as well as a factory controlled by the president dogged Poroshenko before this election.
After the vote, Poroshenko lashed out at Zelenskiy, describing him as a "puppet" of self-exiled billionaire businessman Igor Kolomoyskyi, a charge that Zelenskiy denies. Zelenskiy shot back, saying mockingly that it's impossible to say whether a corrupt official allegedly involved in the military embezzlement scheme was Poroshenko's puppet, or the other way round.
Voters on Monday were ready for the presidential runoff. "Poroshenko is taking the country forward," said Serhiy Poltorachenko, a bank employee. "He made mistakes, but promised to correct them." Petro Demidchenko, a 38-year-old office worker, was supporting the actor.
"We don't know what to expect from Zelenskiy, but over the past five years we have found out what to expect from Poroshenko — corruption, soaring prices, continuing war and poverty," he said.
Mstyslav Chernov in Kiev, Ukraine, Vladimir Isachenkov and Nataliya Vasilyeva in Moscow contributed to this report.