Thousands of opposition supporters celebrated the passage of reforms and constitutional changes that could help Yushchenko win the 26 December repeat election.
Parliament also voted to fire the leader of the Central Election Commission, other members of his team, and General-Prosecutor Hennadiy Vasiliev. Vasiliev was accused by the opposition of colluding in election fraud.
Opposition member Mykola Tomenko told demonstrators yesterday night that they had achieved a great victory.
"We have won this battle and I greet all of you," Tomenko said. "I bow deeply to the ground for your unprecedented heroism, your self-sacrifice, your pride, courage and honesty. Because it is you who are the victors in this battle for Ukraine."
The reforms to election laws were widely viewed by the opposition as necessary to prevent the massive fraud that invalidated the earlier 21 November vote, which saw Prime Minister Viktor Yanukovych originally declared the winner.
The presidential changes, however, are more controversial. And some in the opposition fear they might weaken Yushchenko's chances of fighting corruption should he win on 26 December.
One of the leading members of the opposition, Yuliya Tymoshenko, said she believes the opposition conceded too much and the powers of the presidency should not be weakened.
The changes to the presidency will take effect only after September 2005. The hope is that Yushchenko would still have several months of a strong presidency to carry out the anticorruption and other legal reforms the opposition is seeking.
A parliamentary deputy from Yushchenko's Our Ukraine bloc, Roman Zvarych, said: "I think Yushchenko will be able to rid the country of most of the people who are corrupt and prevent democracy and install people committed to democracy." He said that should ensure fair 2006 parliamentary elections and a pro-democratic majority.
The head of Kyiv's independent Institute of Statehood and Democracy, Ivan Lozowy, said he believes the opposition did not have to concede as much as it did. But he said the concessions may lead to a more orderly poll by helping to convince outgoing President Leonid Kuchma that he will not be prosecuted after the election.
"But on the other hand, there is a positive side from the constitutional and electoral law changes that were attained in parliament with the help of president Kuchma, and that's a gesture by Leonid Kuchma which may give him reason to think that nobody will hound him after the election," Lozowy said. "And that means that the electoral campaign until 26 December, will be calmer."
Lozowy said he believes Yushchenko will still have enough time to sack many local politicians and bureaucrats who have been a brake on political and economic reform.
Yushchenko has now called on supporters to go home and work as election campaigners and to sign up as election observers. But many were determined to stay in Kyiv until after the repeat of the election, living in hundreds of tents pitched on the capital's main Khreschatyk Street.
Many, from the Pora (It's Time) youth organization have pledged to carry on picketing government buildings and Kuchma's country retreat.
Natasha Dyonina, a student who has lived for more than two weeks in the tents, was optimistic after the events in parliament.
"Well, I believe that we can say we have achieved half the victory, but I think that there will only be a complete victory after the election and we will remain until that day of victory -- 26 December," Dyonina said.