Viktor Yanukovich, humiliated in the 2004 "Orange Revolution", could cap a remarkable comeback tomorrow after Ukraine President Viktor Yushchenko nominated him as prime minister to end four months of political deadlock.
Mr Yushchenko, who defeated Mr Yanukovich in the 2004 election, accepted he had run out of constitutional options in the early hours of today and reluctantly turned to his rival after Mr Yanukovich signed a commitment to adopt pro-Western policies.
A vote in parliament to confirm Mr Yanukovich was delayed until tomorrow to allow more time to thrash out details of a "grand coalition" uniting the president's Our Ukraine Party with Mr Yanukovich's Regions group.
The two rivals have formally signed a declaration of principles for the new government. The president said the declaration, his condition for nominating Mr Yanukovich as prime minister, would safeguard the ideals of the "revolution".
Mass protests overturned Mr Yanukovich's election as president in 2004 and swept Mr Yushchenko to power in the ex-Soviet republic. Now Mr Yanukovich, who served as prime minister from 2002 to 2004, will share power with the president and his allies are expected to dominate cabinet.
The United States, which supported the Orange Revolution, said it was happy to work with Mr Yanukovich.
US state department spokesman Sean McCormack said Mr Yanukovich's rise showed the evolution of a democratic process in Ukraine.
"Mr Yanukovich has come to the prime ministership in the old-fashioned, democratic way - he worked hard for votes, he campaigned, he politicked," added Mr McCormack.
The Regions won most votes in March's parliamentary polls in which Mr Yushchenko's Our Ukraine party trailed a poor third, but no party won a clear majority.