Early results from Ukraine's presidential election show billionaire candy maker and former prime minister Petro Poroshenko with a commanding lead.
The country's election commission said Monday that Poroshenko led with 54 percent of the vote with about a third of the ballots counted.
Former prime minister Yulia Tymoshenko was in second place with 13 percent.
Poroshenko claimed victory Sunday after exit polls showed him winning 56 percent of the vote, and said he is ready to negotiate with Russian officials.
"I really hope that the current election which was really free, really fair, the level of the activity of Ukrainian people and Ukrainian voters clearly demonstrate that Ukraine are decisive in building up their future. And I think that Russia is our neighbor, and without Russia it would be much less effective or almost impossible to speak about the security in the whole region or maybe about the global security," said Poroshenko.
Pro-Russian separatists threatened to disrupt the vote and blocked access to polling places in eastern Ukraine. No voting stations were open in the separatist-controlled city of Donetsk, while a scant 16 percent voter turnout is reported in the entire Donetsk region.
President Barack Obama congratulated the Ukrainian people for making their voices heard over the violence and provocations. He said Ukrainians have repeatedly shown their desire to choose their own leaders and live in a democracy.
Obama said the United States looks forward to working with the new Ukrainian president and the elected parliament.
Russian President Vladimir Putin has promised to recognize the outcome of the election, despite expressing misgivings about its legitimacy. He also said he hopes Ukraine's new president will end military operations against separatists in the east.
Sunday's election was the climax of sometimes violent anti-government protests that started last year and drove pro-Russian president Viktor Yanukovych from power. It also led to a Russian takeover of Crimea, a Russian-speaking Ukrainian peninsula.