Exit polls showed pro-Russian candidate Viktor Yanukovych with a narrow lead in Ukraine's presidential runoff, a result that would close the book on Ukraine's pro-Western Orange Revolution but raise the risk of postelection unrest.
Yanukovych went ahead and declared victory, but his opponent Prime Minister Yulia Tymoshenko, a leader of Orange forces, rejected the exit poll data and said Sunday's race was too close to call.
"It is too soon to draw any conclusions," she said, urging supporters to fight for every ballot.
Ukraine's Central Election Commission reported early Monday that opposition leader Yanukovych was leading Tymoshenko by 51.3 percent to 43.3 percent with 27.4 percent of the vote counted.
The National Election Poll exit survey predicted that after the count, Yanukovych would capture 48.5 percent of the vote to 45.7 percent for Tymoshenko, with other voters mostly choosing "Against all." The 2.8 percentage point gap is only slightly larger than the NEP's margin of error of plus or minus 2.5 percent.
The NEP poll initially showed Yanukovych with a 3.2 percentage point lead, but the later released revised figures. All other major exit polls had Yanukovych winning, some by larger margins.
The race narrowed sharply from the first round vote on Jan. 17, when Yanukovych held a 10 percent lead.
At the Yanukovych camp, top party officials broke into rapturous applause as they heard the exit polls announced, and Anna German, deputy head of Yanukovych's Party of Regions, called on Tymoshenko to concede.
"The first rule for a true democrat is to accept defeat when that is the will of the people," she said. "It is now Yulia Tymoshenko's responsibility to do that."
Tymoshenko has vowed to challenge a vote she claims was rigged by in Yanukovych's favor, as it was in the 2004 elections that set off the Orange Revolution. After weeks of demonstrations, a court threw out the results of that 2000 vote contest and Yanukovych lost a court-ordered revote to Orange forces
Tymoshenko's campaign chief Alexander Turchinov insisted Sunday there was evidence of fraud. "Intrigue still remains in place, we remain certain," he said.
But Matyas Eorsi, head of the Parliamentary Assembly of the Council of Europe's election observation mission, called the balloting "calm" and "professional" and said there was no evidence the vote had been stolen.
"We are 100 percent sure that this election was legitimate," Eorsi said. "All the international community, and even more important, the Ukrainian public can accept this result."
A preliminary report by international monitors is expected later Monday.
Mikhail Okhendovsky, a member of Ukraine's Central Election Commission, said the board had no evidence of large scale falsification but expects that the loser will challenge the results in court anyway.
"In keeping with the traditions of Ukrainian elections, the loser never accepts defeat," he said before the polls closed.
The Central Election Commission projected the turnout among Ukraine's 37 million voters at about 70 percent, 3.2 percentage points higher than the Jan. 17 first-round vote in which 18 candidates competed.
Early figures showed a heavier turnout in Yanukovych's strongholds in Ukraine's Russian-speaking east than in Tymoshenko's districts in the country's Ukrainian-speaking west.
Tymoshenko's impassioned leadership of the 2004 Orange protests made her an international celebrity, and she fought hard in recent weeks to rekindle the heady emotions those days. At one point she debated an empty lectern to dramatize her opponent's refusal to debate her.
She sought to depict herself as a populist whose appeal crossed Ukraine's east-west divide but she bore the scars of five years of political battles with Yanukovych and her sometime Orange ally, outgoing President Viktor Yushchenko, and has struggled to cope with Ukraine's severe economic crisis.
Ukraine has been among the hardest-hit nations in the global credit crunch. Its currency crashed in 2008, wiping out almost half of people's savings, and the International Monetary Fund had to step in with a $16.4 billion bailout. GDP plunged more than 14 percent in 2009 and the country is expected to have only anemic growth this year, according to the World Bank.
As the election approached, Yanukovych, awkward when speaking in public, tread carefully, sticking mostly with photo opportunities and bland statements to try to hang onto his lead.
He would not be drawn into a Russia-versus-West debate, and pledged to balance ties between Ukraine's diverse neighbors.
"Ukraine will never be a friend with Russia at the expense of Europe, or Europe at the expense of Russia," said Boris Kolesnikov, deputy leader of Yanukovych's Party of Regions. "That will guide the foreign policy under the Yanukovych presidency."
But Yanukovych represents the hopes of many Russian speakers in eastern Ukraine, who feel they have been relegated to second-class status behind the urban elite who favored the Orange reform forces.
Yanukovych supporters have been camped out in front of the Central Election Commission headquarters and other key points in Kiev in an apparent effort to prevent Tymoshenko supporters from staging mass demonstrations like those of the Orange revolt.
If Yanukovych wins, it will be an impressive reversal of fortune. During the 2004 protests, foes cast him as a Kremlin lackey. But he battled back, serving for a time as prime minister under his main Orange adversary, Yushchenko.
He gained ground as voters said they were weary of broken promises, a dysfunctional economy and political chaos under the Orange government.
Casting his ballot in Kiev, once an Orange bastion, Yanukovych said the election would mark the "first step in overcoming the crisis."
"The people of Ukraine deserve a better life, so I voted for positive changes, stability and a strong Ukraine," he said.
Tymoshenko voted in her hometown, the industrial center of Dnipropetrovsk, in Yanukovych's stronghold of eastern Ukraine.
"I voted for a new Ukraine a beautiful and European Ukraine and for people to live happily. I will serve Ukraine with all my heart," Tymoshenko said, standing next to her husband.
Sunday's vote may shift the balance of power in Ukraine, but it will not heal the country's deep divisions.
"I am voting against the return of our Soviet past," 40-year-old businessman Vladimir Khivrenko said at a polling station near the Maidan, the central square in Kiev, the capital. "Tymoshenko has promised us a new path to Europe, and I believe her."
Tatyana Volodaschuk, 60, said she was sick of political uncertainty.
"I want stability and order," she said. "Yanukovych offers us the guarantee of a normal life."