Ukraine's President Viktor Yushchenko has begun separate coalition talks with political rivals who beat him into third place in the general election.
Yanukovych, Tymoshenko and Yushchenko have hopes of power
He may try to reunite with his former Orange Revolution ally Yulia Tymoshenko to thwart the pro-Russia party leading with two-thirds of the votes counted.
The party of Viktor Yanukovych has just under 30% - a strong comeback following his presidential election defeat.
Many voters turned against the Orange Revolution which defeated him in 2004.
President Yushchenko's liberal Our Ukraine party is trailing in third place with 15%.
Mr Yushchenko is expected to spend Tuesday in negotiations with Mr Yanukovych and Ms Tymoshenko, whom he sacked as prime minister last September.
Ms Tymoshenko's bloc is in second place, with 22.4%. Final results are expected later on Tuesday.
Mr Yushchenko said the talks would focus on "a joint action plan that would ensure stable national development for the next four years".
'Free and fair'
The Socialist Party and the Communist Party have both crossed the 3% threshold needed for parliamentary representation.
A total of 45 parties were on the ballot papers.
Observers from the Organisation for Security and Co-operation in Europe (OSCE) have described the election as "free and fair".
Mr Yanukovych was declared the winner of the presidential election in November 2004, but allegations of widespread vote-rigging sent hundreds of thousands of Ukrainians out onto the streets to demand change.
In what became known as the Orange Revolution, the election result was overturned and Mr Yushchenko went on to win a re-run.
But Mr Yushchenko's popularity has plunged following a year of political infighting and sluggish economic growth.
The president fell out with some of those who stood beside him on the stage in Kiev during the revolution, including Ms Tymoshenko.
Now it looks like the pro-Western liberals will join forces again, but this time Ms Tymoshenko is in a commanding position, the BBC's Helen Fawkes reports from Kiev.
Mr Yushchenko's chief-of-staff, Oleh Rybachuk, told the BBC's Newshour programme that so far the two sides had done little more than announce their intentions.
"I do not expect any formal agreement signed, neither today nor in the nearest future," he said.
Ms Tymoshenko has said she wants to return to the post of prime minister.
She has also vowed to cancel a controversial gas deal Ukraine signed with Russia.
Both of these proposals would be difficult for Mr Yushchenko to accept, but he has been left with few options, our correspondent says.