Ukrainian businessman, politician and presidential candidate Petro Poroshenko, left front, and his wife Maryna, right front, cast their votes during the presidential election at a polling station in Kiev on Sunday. — Reuters KIEV/MARIUPOL, Ukraine — Ukrainians were set to give a resounding endorsement to the overthrow of their last elected leader by voting on Sunday for presidential candidates promising close ties with the West in defiance of Russia's Vladimir Putin. But the absence of over 15 percent of the electorate, in Russian–annexed Crimea and two eastern regions where fighting with pro–Moscow rebels continued on Saturday, may mar any result — and leave the Kremlin questioning the victor's legitimacy, for all President Putin's new pledge to respect the people's will. Voting began in most of Ukraine at 8 a.m. (0500 GMT) and end 12 hours later, when exit polls will indicate a result ahead of an official outcome on Monday. But many voters in the Russian–speaking east will find polling stations shut. European election monitors largely pulled out of Donetsk region for their own safety, citing a campaign of “terror” by pro–Russian separatists against Ukrainian electoral officials. Polls make a billionaire confectionery magnate known as the “chocolate king” overwhelming favorite, with a high turnout expected on a warm day. The biggest question is whether Petro Poroshenko can take over 50 percent to win in a single round. He was a strong backer of the protests against Moscow–backed president Viktor Yanukovich last winter and has sought a quick victory by warning that new unrest might prevent a second round. His closest, if distant, rival is Yulia Tymoshenko, a former prime minister. She seems best placed to contest a runoff in three weeks, but remains a divisive figure to many, more closely linked with the economic failures and corruption that have blighted 23 years of independence. As Yanukovich's fiercest rival, she may benefit from the fact that few of the 5 million voters in his eastern power base regions of Donetsk and Luhansk may be able to cast ballots for any of the 21 candidates. Officials say many polling stations will not open for fear of attack and only early on Sunday they distributed ballot papers to those areas where voting may be possible. Interim Prime Minister Arseny Yatseniuk said on Saturday the act of voting would be victory, hand the new president a mandate to forge closer ties with the European Union and move Ukraine away from a “grey zone of lawlessness and dark forces that dream of suffocating us and into ... a place where it is easier to breathe.” Western states backed those who took power when Yanukovich fled to Russia three months ago after street protests triggered by his rejection of a free trade pact with the EU. They hope that a mandate for a new leader can help resolve a confrontation with Russia that has sparked military buildups east and west of Ukraine and raised fears of a new Cold War. The Russian president pledged on Saturday to “respect” the people's choice and work with Ukraine's new administration – a conciliatory move during an economic forum at which he had acknowledged that US and EU sanctions over Ukraine were hurting the Russian economy. — Reuters