Initial exit polls suggest the pro-Russian opposition party, led by Viktor Yanukovych, will win at least 33% of seats in Ukraine's parliamentary election.
The election is the first since the Orange Revolution that brought President Viktor Yushchenko to power.
The polls have placed Mr Yushchenko in third place with 13.5% of the vote.
The first official results are expected early tomorrow, but no party is expected to win enough seats to govern alone.
Mr Yushchenko had urged voters to back his party, calling it a choice between 'the past and the future'.
He is seeking a stable majority in order to continue reforms aimed at driving Ukraine towards membership of the European Union and NATO.
But the widespread support Mr Yushchenko enjoyed when he assumed power has since weakened and the Orange Revolution team has broken up amid mutual recriminations.
