Ukraine's parliament adopted electoral and constitutional changes Wednesday in a compromise intended to defuse the nation's political crisis — prompting opposition leaders to say they would lift a two-week blockade of government buildings.

The vote came as a surprise after days of political maneuvering and massive street protests following the disputed Nov. 21 presidential runoff election. It suggested that opposition leader Viktor Yushchenko's (search) camp had determined that the prolonged unrest could ultimately weaken the country and his own position ahead of a Dec. 26 rerun of that vote.

The package was approved in a 402-21 vote with 19 abstentions, drawing an endorsement from Yushchenko's supporters. Lawmakers stood and cheered as President Leonid Kuchma (search) signed the measure.

"Today was the day for critical compromise," a jubilant Yushchenko said outside the doors of parliament after the laws passed. "Tomorrow could have been too late."

The United States and other Western governments praised the decision, coming after a tense two weeks of round-the-clock street protests in Kiev.

"Ukrainians are coming together to find a Ukrainian solution," Secretary of State Colin Powell said in a speech in Brussels, where he was attending NATO talks.

The European Union's foreign policy chief, Javier Solana, also congratulated "all sides on the crucial decisions that were taken today" in a letter obtained by The Associated Press.

After signing the text of the amendments and laws package in two blue leather folders with a golden Ukrainian trident, Kuchma shook hands with parliament speaker Volodymyr Lytvyn and deputy speakers. Lytvyn then firmly clasped both folders and held them up to show to deputies.

"Over the last 100 years, Ukraine has more than once suffered through a crisis, but there was always enough common sense to find a way out and a decision," Kuchma said.

Campaigning in eastern Ukraine, Prime Minister Viktor Yanukovych (search), the Kremlin-backed candidate whose support in Ukraine is slipping away, said he was "not happy" with parliament's decision. He described it as a "soft coup d' etat."

"All the decisions were made under pressure," Yanukovych said, apparently referring to opposition protests.

The opposition planned to end its blockades of government buildings Wednesday evening, said Socialist Party leader Oleksandr Moroz, a key Yushchenko ally.

The blockades of the buildings paralyzed government operations and preventing Kuchma and Yanukovych from reporting to work. On Monday, the demonstrators began letting through some workers, but refused to allow in senior government officials.

As word spread of the parliament's decision, demonstrators — exhausted and haggard after the blockades and demonstrations in Kiev's freezing streets — expressed relief.

"Some kind of compromise had to be reached," said Serhiy Vlasov, 44, who wore a pro-Yushchenko orange band tied around his arm. "We couldn't drag this out forever."

Yushchenko's camp had pushed strongly for electoral changes to close loopholes for fraud ahead of the new vote, but they had resisted the constitutional changes, which would transfer some presidential powers to parliament.

A group of communist, socialist and pro-government factions in parliament agreed to the electoral changes on condition they were voted together with the constitutional changes.

In the final version approved Wednesday, the president no longer has the power to appoint his own government, but keeps the right to reject parliamentary nominees for the top three positions — prime minister, foreign minister and defense minister. Parliament also earns the right to appoint all other Cabinet positions without presidential approval.

To prevent electoral fraud in the new ballot, restrictions were placed on absentee voting.

Also, Kuchma said he accepted the resignation of the prosecutor general, a key opposition demand.

The parliament returned after a brief recess and began to reshuffle the Central Election Commission, which had declared Yanukovych the winner of the runoff that was marred by allegations of fraud, beginning Ukraine's crisis.

Lawmakers voted to oust the election commission's chief, Serhiy Kivalov, and a decision to nominate him was met with shouts of "Shame!" by Yushchenko supporters.

Yushchenko is backed by the Ukrainian-speakers who want to end what they say has been mass corruption during Kuchma's 10 years in power. Yushchenko wants to take Ukraine into the European Union and NATO. Yanukovych draws his strength from the Russian-speaking, industrial east, which accounts for one-sixth of Ukraine's population.

In a separate development, the director of the Austrian hospital said the cause of the illness that left Yushchenko's face pockmarked is still not known, rejecting a report that doctors had come to a conclusion that the presidential candidate was poisoned.

Yushchenko has accused the Ukrainian authorities of poisoning him during the campaign leading up to last month's disputed presidential election, something they deny.

Doctors are still running tests to try to determine what caused the illness, said Dr. Michael Zimpfer, the Rudolfinerhaus director, although he acknowledged that poisoning was one of the possibilities being investigated.

Zimpfer rejected as "entirely untrue" a story in Wednesday editions of the London daily, The Times, which quoted Dr. Nikolai Korpan — the Rudolfinerhaus physician who oversaw Yushchenko's treatment — as saying that the candidate had been poisoned and the intention was to kill the candidate.

Korpan also was quoted as denying making the remarks.

"The suspicion of poisoning has until now neither been confirmed or excluded," Korpan said, according to the Austria Press Agency. He could not be reached for further comment.

Zimpfer said doctors had only "a descriptive diagnosis" but were still trying to determine what had caused the illness.

It could have had natural causes, or it could have been a poison, Zimpfer said, adding that "it might also have been a combination of poisons. Everything is in the air."

Still, The Times report had prompted one group of exhausted opposition supporters from the central city of Zhitomyr to change its plans.

"We were packed and about to leave when a man told us about the article ... now we will stay. Someone will pay dearly for what they have done to him (Yushchenko)," said Evhen, who revealed only his first name.