Comedian and leading Ukrainian presidential candidate Volodymyr Zelenskiy awaits voting results at his election night gathering, March 31, 2019 in Kiev, Ukraine. Getty

Kiev, Ukraine -- Early results Monday in Ukraine's presidential election showed a comedian with no political experience maintaining his strong lead against the incumbent in the first round, setting the stage for a presidential runoff in three weeks. With over 70 percent of the polling stations counted, Volodymyr Zelenskiy had 30 percent support in Sunday's vote, while President Petro Poroshenko was a distant second with just over 16 percent.

Ex-Prime Minister Yulia Tymoshenko trailed behind in third with 13 percent 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.

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"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 to be announced later Monday.

With the lineup for the presidential runoff becoming clear, voters were picking sides.

"Poroshenko is taking the country forward," said Serhiy Poltorachenko, a bank employee. "He made mistakes, but promised to correct them. Poroshenko will win, because Ukrainians won't like to have a clown at the country's helm."

Petro Demidchenko, a 38-year-old office worker, said he was supporting Zelenskiy.

"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.

Like the character he plays in a TV sitcom, a schoolteacher-turned-president, 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.

Russia looms over the vote

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 rebels in the east and to wrest back control of Crimea, the Black Sea peninsula that Russia annexed in 2014 in a move that has drawn sanctions against Russia from the U.S. and the European Union.

Asked about Sunday's vote, 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.

CBS News and CNET senior producer Dan Patterson says the Ukrainian vote has also been watched closely in cybersecurity circles, given Russia's well-documented record of interference in democratic processes -- using techniques it has pioneered in neighboring Ukraine.

The New York Times reported that Facebook has removed at least 2,000 accounts -- most of them linked to Russia -- suspected of spreading misinformation in the run-up to the vote, but that the social media giant has been accused by cyber experts of doing too little too late to thwart the long-expected Russian interference efforts.

In response to changes Facebook has made in the wake of the outcry over Russian meddling in U.S. politics, the Times said Moscow changed its tactics ahead of this Ukrainian election, trying to find Ukrainian nationals willing to sell or rent their own accounts out to Russian propagandists.

Zelenskiy's campaign had complained to Facebook repeatedly over delays in getting their official Facebook and Instagram pages verified by the social media giant amid a proliferation of fake sites.

Claims, and denials, of fraud

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 places.

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.

"No systematic violations took place on either the election day or the night following the election when votes were being counted at the local polling stations," said Central Election Commission head Tetyana Slipachuk.

Poroshenko looked somber as the votes came in, but visibly relieved about surpassing Tymoshenko to advance to the runoff.

"I critically and soberly understand the signal that society gave today to the acting authorities," he said. "It's a tough lesson for me and my team. It's a reason for serious work to correct mistakes made over the past years."

Still, it's not clear whether he could adjust his campaign enough to meet Zelenskiy's challenges over the next three weeks.