Ukraine's opposition leader Viktor Yushchenko (search) signed a deal Wednesday that obliged his supporters to lift their siege of government buildings, but he said his followers will stay on the streets until an agreement is reached on a new vote for the country's presidency.

Yushchenko held face-to-face talks with Prime Minister Viktor Yanukovych (search) — his rival for the presidency — hours after the opposition showed its strength by bringing down Yanukovych's government with a no-confidence in parliament.

After the talks, Yushchenko proposed that a new run-off vote between him and Yanukovych be held Dec. 19. Speaking to his supporters in the street, he said he would not accept a whole new election — an idea suggested earlier by outgoing President Leonid Kuchma (search) — and urged his backers not to give up their massive demonstrations.

"Protests in the streets will, of course, continue," Yushchenko said after the talks at the Mariinskly Palace presidential residence. "They would be lifted only after a date is set for a new election and changes introduced into the election law."

Holding an entire new election would allow other candidates to enter the race again, which the government apparently hopes would weaken Yushchenko. A repeat of the run-off as the opposition seeks would limit the contest to the rivals.

Hundreds of thousands of Yushchenko supporters have been in the streets of the capital, Kiev, claiming that fraud in the Nov. 21 run-off robbed the opposition leader of victory. Official results called Yanukovych the winner.

Under Wednesday's agreement between the two rivals — also signed by Kuchma and European mediators — opposition supporters would lift their blockade of the presidential administration and Cabinet buildings in Kiev.

It was unclear whether the agreement extended to massive pro-Yushchenko protests in Kiev's central square.

Under the deal, a group of lawyers would be convened immediately to consider changes in Ukrainian law in a bid to resolve the crisis. Yushchenko told reporters the lawyers must come up with proposals within 24 hours.

Earlier Wednesday, Kuchma — who has backed Yukovych to succeed him — said he supported holding an entire new presidential election, but denounced the idea of repeating just the second round.

"Where in the world do they have a third round of elections? A revote — it's a farce," Kuchma said at a government meeting. "I never supported it because it is unconstitutional."

Ukraine had a first round of voting with a crowded field of 24 candidates in which no one received more than half the votes, setting up the Nov. 21 runoff. International monitors and Western governments — including the United States — have denounced the run-off results, citing fraud in favor of Yanukovych.

European Union foreign policy chief Javier Solana and the presidents of Poland and Lithuania helped mediate the agreement, along with the head of the Organization for Security and Cooperation in Europe (search).

At the same time, the two sides were slugging it out at the Supreme County. The court met for the third day to consider Yushchenko's appeal against the runoff results, and the prime minister struck back by filing his own complaint. Yanukovych sought to have the court invalidate results in several districts won by Yushchenko, justices said. It was unclear whether the court would hear Yanukovych's appeal.

The opposition succeeded in undermining Yanukovych with Wednesday's no-confidence vote in parliament. The measure passed with 229 votes in the 450-seat parliament, three more than necessary. Outside the building, a crowd of opposition supporters, listening to a live translation, broke into applause, chanted "Yushchenko!" and raised their fists in triumph.

The measure automatically triggers the resignation of Yanukovych's government. Kuchma can, however, allow the government to continue to exercise its powers until a new Cabinet is formed, but not for longer than 60 days.

Kuchma called the vote "the parliament's answer to the worsening political situation in Ukraine," said his spokeswoman Olena Hromnitskaya. She said Kuchma "will act within the framework of the Constitution."

Kuchma is likely to name parliament speaker Volodymyr Lytvyn to head a caretaker government, said Markian Bilynskyj, a Kiev-based analyst.

Meanwhile, the regional legislature in Yanukovych's eastern home region of Donetsk decided to hold a referendum on Jan. 9 seeking a measure of autonomy from the country's central government — a move that could transform Ukraine into a federation-style government.

Governor Anatoliy Bliznyuk said the region wanted to transform Ukraine into a federation but was not seeking full autonomy.

The move reflected government supporters' warnings that the opposition demands will split Ukraine, a nation nearly the size of Texas. Yanukovych's base of support lies in the Russian-speaking, industrialized east, where many support close ties with Moscow. Yushchenko draws his support from the Ukrainian-speaking west and the capital.