Timoshenko says she and Yushchenko had signed an agreement to appoint her as prime minister after the inauguration because of her support to the newly-elected president, reports Novosti news agency.
"I do not doubt the fact that Parliament will support my candidacy as prime minister, if Yushchenko suggests it," Timoshenko said.
Timoshenko must collect a simple majority of all votes from the 450-member parliament.
Some critics believe the appointment of Timoshenko will increase the rift between western and eastern Ukraine.
Yushchenko, who won the second round of Ukrainian presidential elections on Dec. 26, has refused to discuss any appointment until after the inauguration.