The party of a reformist former premier topped Ukraine's parliamentary election on Sunday, according to an exit poll.
The result, giving Mr Viktor Yushchenko's Our Ukraine Party a clear lead with 25 per cent of the party list vote, could confound critics who predicted a poll rigged in favour of parties loyal to President Leonid Kuchma.
The exit poll, commissioned by a Western-funded organisation called Renaissance, put the Communist Party second, with 20.5 per cent, and the pro-presidential bloc third, with 10.6 per cent.
Ms Julia Tymoshenko, a fierce Kuchma critic, was placed fourth, with 7.9 per cent of the vote, with the pro-presidential Social Democratic Party United fifth, with 7.1 per cent, and the Socialist Party taking 6.1 per cent.
"The remaining parties have not cleared the barrier," Ms Irina Bekeshchkina, head of a fund called Democratic Initiatives, told a news conference after polling stations shut across the country, the size of France.
Thirty-seven million Ukrainians were registered to vote in the third general election since independence, choosing from an array of 33 parties.
The polling groups interviewed 18,000 voters at random as they left voter stations throughout the country. The survey was carried out by Ukraine's leading polling firms KIIS (the Kiev International Institute of Sociology), Democratic Initiative and SOCIS.
A separate exit poll of about 8,000 people, conducted by the Ukrainian Centre for Social Research and the Ukrainian Centre of Political Management, found similar results.
Preliminary election results are due today. Turnout was 39 per cent at 3 p.m., according to the former Soviet republic's Central Election Commission, which nevertheless pronounced the poll free and fair, despite opposition claims that President Kuchma had sought to manipulate the outcome.
The final countdown to polling was overshadowed by the murder of a pro-business candidate in the western Ivano-Frankivsk region, whose death underscored Western fears about Ukraine's fragile democracy.
Communist Party leader Mr Leonid Simonenko said his group was seeking impeachment of the President no matter how the vote turned out.
"This is our position and we will not turn away from it," Interfax news agency quoted Mr Simonenko as saying.
International concern about the elections has prompted almost 1,000 monitors from the Organization for Security and Co-operation in Europe, the Council of Europe and the Commonwealth of (ex-Soviet) Independent States to gather in Ukraine to oversee polling.