By Natalya Zinets and Yuri Kulikov
KIEV (Reuters) - Ukraine's ruling coalition collapsed on Tuesday as newly elected President Viktor Yanukovich moved to oust Prime Minister Yulia Tymoshenko and consolidate his power.
Parliament speaker Volodymyr Lytvyn said leaders of parliamentary factions had met and the coalition partners had failed to submit enough signatures to demonstrate they maintained a majority.
Tymoshenko, the fiery co-architect of the pro-Western Orange Revolution of 2004, remains in office, but faces a vote of no confidence in her government on Wednesday as Yanukovich goes through the steps of tightening his grip on power.
She indicated that if the vote succeeds, she might step down, so that "all responsibilities will immediately be laid on Yanukovich."
His victory over Tymoshenko in an acrimonious and tightly-fought February 7 run-off election is expected to tilt the country of 46 million people back toward Russia after years of infighting between the Orange revolutionaries.
Tymoshenko has refused to recognize Yanukovich's victory and lashed out on Tuesday at her former allies in parliament, telling reporters: "Today they destroyed the last bastion, the last barricade defending our Ukraine."
A formal announcement of the collapse of the coalition and a motion of no confidence in the government have to occur for Yanukovich's supporters to begin the difficult process of creating a new government.
Ukraine desperately needs political stability to tackle a debilitating economic crisis that saw GDP contract by 15 percent in 2009, and to restart talks with the International Monetary Fund on a $16.4 billion bailout package.
Deputy Finance Minister Oleksander Savchenko said the IMF was unlikely to return before the second half of the year and in the meantime Ukraine would need to find billions of dollars to cover the government's spending and debt payments.
"Until the IMF comes back -- I think in the third quarter it will start financing Ukraine -- we need per quarter minimum $3 billion and maximum $5 billion in order to cover our spending," Savchenko told journalists.
Investors have been worrying about a sovereign default for a year, but this has not happened and the government has only one Eurobond to pay back this year, in December. But the government's domestic debt payment burden is heavy.
The collapse of the coalition suggests that the no-confidence vote will pass.
Weeks of horse trading would likely follow as Yanukovich's Regions Party works to form its own coalition and, later, a new government. The various parliamentary factions have 30 days to form the new coalition and 60 days to form a new government.
If this proves impossible, Yanukovich has the right to call a new parliamentary election -- a scenario feared by investors because it would prolong uncertainty for months as Ukraine continues to struggle without foreign lenders.
If Wednesday's vote passes, Tymoshenko would be expected to stay on as acting premier until a replacement is voted in. But on Tuesday she sent signals that she might not stick around, spelling further uncertainty for the country.
Asked if she would quit her office if the vote passes, Tymoshenko replied: "Absolutely. If the government is dismissed, all responsibilities will immediately be laid on Yanukovich."
Yanukovich, a beefy ex-mechanic from the Russian-speaking east, has named three likely candidates for premier: reformist former central bank chairman Sergey Tigipko, former foreign minister Arseniy Yatsenyuk and Russian-born former finance minister Mykola Azarov, a close ally of Yanukovich.
To form a coalition, Yanukovich's Regions Party has to poach dozens of deputies from the Our Ukraine faction, an alliance of myriad parties once grouped around former president Viktor Yushchenko and part of the outgoing coalition.
"To dismiss Tymoshenko tomorrow is not a problem," said analyst Mikhail Pogrebinski, "but as for a coalition -- that's not clear."