Billionaire businessman Petro Poroshenko was elected the next president of Ukraine on Sunday, winning a landslide mandate to start tackling the country's twin crises of pro-Russian separatism and a broken economy.

Mr. Poroshenko – a long-time kingmaker in Ukrainian politics who finally sought the throne for himself following the February overthrow of Viktor Yanukovych – claimed victory minutes after two exit polls showed he had won upward of 55 per cent of the national vote. Though official results were much slower to trickle in, the chocolates-and-media tycoon looked to be comfortably over the 50 per cent line required to avoid a second-round run-off vote in three weeks' time.

He said his first task would be to fly to the violence-racked southeast of the country to meet with residents to tell them the Russian language and culture would be protected inside Ukraine, though he vowed not to meet with the pro-Russian gunmen who have taken over government buildings and battled the Ukrainian army.

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Hours after Mr. Poroshenko proclaimed victory, Ukraine's Interfax news service reported that the government's "anti-terrorist operation" against separatists in the Donetsk and Lugansk regions would resume after an election-day pause. Separatist gunmen in these regions prevented most polling stations from opening on Sunday.

Mr. Poroshenko vowed to pursue integration with the European Union, as well as direct negotiations with Russian President Vladimir Putin.

The Odessa native appeared to have been carried to victory by widespread crisis fatigue that translated Sunday into mass strategic voting.

After six months of chaos in the country, many voters told The Globe and Mail they were supporting Mr. Poroshenko – who had led opinion polls throughout the race – in order to push him over the 50-per-cent mark and bring the election campaign to a swift end.

Mr. Poroshenko's campaign capitalized on that desire, telling voters in the recent days that a second round run off would prolong the uncertainty about who spoke for Ukraine (Russia has continued to recognize Mr. Yanukovych as president), and that a second-round vote would cost the effectively bankrupt country millions of dollars that it couldn't spare.

"All the exit polls, without exception, are saying, decisively that the election has ended in one round and the country has a new president," Mr. Poroshenko told a businesslike press conference just 15 minutes after voting ended. "The first steps that we will take, at the beginning of the presidential [term in] office, will be focused on stopping the war, this chaos, bringing peace to the Ukrainian land."

Mr. Poroshenko's campaign headquarters reacted with only restrained applause to the exit-poll results. His downbeat victory speech reflected the anxious mood in the country. "We need to have a president who is elected today," rather than after three more weeks of campaigning, said Anatoliy Fishchuk, a 30-year-old aircraft engineer who cast his vote for Mr. Poroshenko Sunday in a suburb on the western edge of Kiev. "The situation on our eastern border is not quiet. Only a new president can solve this."

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Voter turnout was reported at over 60 per cent across the country. It wasn't immediately clear whether that number accounted for Donetsk and Lugansk, or Crimea, which was included in the vote even though it is now under Russian rule.

Former prime minister Yulia Tymoshenko came a distant second, according to the exit polls, with just over 12-per-cent support. She conceded defeat shortly after Mr. Poroshenko spoke, telling her supporters that she would continue to push for the country to hold a referendum on joining the European Union and NATO.

Mr. Poroshenko said the country had now made its "European choice," but has been less enthusiastic about applying to join the Western military alliance, a move the Kremlin has identified as a red line.

While Moscow made no comment Sunday about the elections, the White House released a statement hailing the vote. "Despite provocations and violence, millions of Ukrainians went to the polls throughout the country, and even in parts of eastern Ukraine, where Russian-backed separatist groups sought to disenfranchise entire regions, some courageous Ukrainians still were able to cast their ballots," U.S. President Barack Obama was quoted as saying.

Canadian Foreign Minister John Baird also cheered the voter turnout. There were more than 350 Canadians serving as observers for the election.

'Despite the violence and aggression that we have seen from pro-Russian separatists and militants, as well as provocative action coming from the Russian Federation, Ukrainians were resilient and brave and turned out in strong numbers, from all accounts right across the country," said MP James Bezan, the head of Canada's parliamentary delegation of election observers with the Organization for Security and Co-operation in Europe.

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In eastern Ukraine, especially in regions such Donetsk and Lugansk where separatists had disrupted voting, Mr. Bevan said arrangements had been made so residents there could travel to other polling stations deemed to be less at risk.

"We knew there was going to be difficulty in those areas," said Mr. Bevan, speaking from the city of Kharkiv, which he described as relatively peaceful on election day.

Mr. Poroshenko said he wanted to soon meet with Russian President Vladimir Putin to hold "direct dialogue to solve the long list of problems that are not caused by Ukraine." Relations with Moscow were the most difficult they had been "for the past 200 years."

Ukraine has railed against Russian backing for the armed uprising in Donetsk and Lugansk, and Mr. Poroshenko said Sunday that his government would "never recognize" Russia's annexation of the Crimean Peninsula following a controversial referendum there in March. Russia, meanwhile, calls the February revolution against Mr. Yanukovych a Western-supported coup d'état, and has demanded Ukraine pay billions of dollars in debts.

Mr. Poroshenko also vowed to call parliamentary elections before the end of the year in order to break a logjam caused by the fragmentation of Mr. Yanukovych's Party of Regions. Mr. Poroshenko said the split parliament was blocking the reform process and "blocking military decisions."

Another issue awaiting the president elect, and his political ally Vitali Klitschko, the former boxing champ whom exit polls suggested had won election as the new mayor of Kiev, is the future of the hundreds of protesters still camped in the middle of Kiev three months after they helped oust Mr. Yanukovych from power.

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With a report from Erin Anderssen in Ottawa