The agreements, however, appeared to be unraveling even before they could be put in effect. Thousands of protesters who have clogged the center of Kiev and blocked or restricted access to many government buildings kept up their cordons.

One of Yushchenko's most prominent supporters, Yulia V. Tymoshenko, said at a press conference on Thursday that any agreement to end the blockades should have been signed "by all the people on Maidan," using the common name for Independence Square.

"Nothing will be unblocked," she declared. "Maidan will not go anywhere."

In a worrisome sign for Yushchenko's support on the streets, a youth movement involved in the protests, Pora, which means "It's time," announced in an e-mail message that it did not support the compromise reached on Wednesday. Kuchma, who returned to Kiev on Thursday evening, offered Yushchenko's supporters a grand bargain. He offered to dismiss Yanukovich's government, which a bare majority of the parliament voted for on Wednesday, but only if the opposition agreed to enact changes in the political system. Implicit in his proposal was that Kuchma would still be in position to appoint the new government.

Tymoshenko insisted that the changes, which would diminish some of the powers of the presidency, could only take effect following new parliamentary elections in 2006, giving Yushchenko more than a year in office with the same powers Kuchma wielded for years.

The Supreme Court, in the meantime, continued its hearings. In the most striking testimony, Ruslan Knyazevich, a member of the Central Election Commission, who refused to sign the official results, said that after polls closed on the night of Nov. 21, computer votes spiked. "One million more votes were thrown in," he testified, adding that many of those came from the eastern regions where Yanukovich, who won by roughly 800,000 votes, polled strongly.

The court began hearing closing arguments Thursday night, but adjourned until Friday.