Speaking after being elected chairman of the Supreme Rada, Volodymyr Lytvyn, who also held the post from 2002 to 2006, said Yulia Tymoshenko was likely to remain prime minister.
"I do not see any grounds for major changes in the government, and above all the prime minister," Lytvyn said.
The groups led by the president, the prime minister, and the parliamentary speaker respectively would have 248 seats in the 450-member Rada. 226 MPs are required to form a majority coalition.
The formation of the coalition would make the holding of early parliamentary elections unnecessary.
However, Lytvyn said the deal had not yet been signed. "It is being discussed and will probably be signed in the next few days," he said.
President Viktor Yushchenko's Our Ukraine and Tymoshenko's bloc split in September over a host of differences, including over Russia's war with Georgia in August. Yushchenko then dissolved parliament and called snap elections, which were subsequently called off after Ukraine's economy was devastated by the global credit crunch.
Yushchenko and Tymoshenko were allies in the 2004 "orange" revolution that swept them to power, but have since drifted apart. Both are expected to run for presidency next year.
The legislature had been without a leader since pro-presidential speaker Arseniy Yatsenyuk was dismissed on November 12 in a vote proposed by the opposition Party of Regions, led by ex-premier Viktor Yanukovych.