Ukrainian President Victor YushchenkoThe governing line-up linked to the 2004 "Orange Revolution" collapsed last month when the president's Our Ukraine party quit its alliance with Prime Minister Yulia Tymoshenko's bloc.
The leaders had stood side by side during the protests that swept the president to power, but have been at odds ever since.
Tymoshenko has made what she presents as concessions to keep the president from dissolving the assembly and calling what would be the third parliamentary poll in as many years.
"I am, naturally, on the side of those voters who would like to see the orange coalition restored," Yushchenko said in an appeal to parliament issued as he left for talks in London.
"But it is plain to all that efforts by Yulia Tymoshenko's bloc to return to a democratic majority are nothing but a political manoeuvre to maintain its own powers and has nothing to do with building a viable coalition..."
Yushchenko acknowledged that "yet another election causes stress in the country. But let us not forget that an early election, while a radical solution, is a constitutional and democratic way out of this crisis."
The president said at the weekend a solid coalition was needed so that Ukraine did not become a "Mexican soap opera and hold elections every 12 months". He said he would otherwise use his right to dissolve the chamber "within days" and scheduled consultations with Our Ukraine deputies for Tuesday.
The differences between the president and prime minister have focused on relations with Russia -- and the Kremlin's role in its war with Georgia -- and a long-running debate on how to divide up power in post-Soviet Ukraine.
Tymoshenko, who has served twice as prime minister, last week said all conditions set by Our Ukraine had been met.
Parliament overturned laws cutting the powers of the president and she signed before television cameras a declaration signed by Yushchenko and European Union leaders upholding Georgia's borders and its right to choose its foreign policy.
Yushchenko had accused Tymoshenko of being soft on the Kremlin so as to curry favour before a 2010 presidential election, the focus of many top Ukrainian politicians.
Talks between Our Ukraine and Tymoshenko's bloc to patch up differences and restore the coalition have made little progress.
Experts differ on when the president can declare an end to attempts to coalition talks and call an election.
None of the major parties stands to gain from an election. Polls show Tymoshenko and ex-prime minister Viktor Yanukovich, the main adversary of the 2004 protests, vying for the lead with about 20 percent. Yushchenko is far back in single figures.