It was the moment for which the crowds filling central Kiev had been waiting. After nearly two weeks in the cold, the demonstrators supporting Viktor Yushchenko, opposition leader, finally had a big victory to cheer in the Supreme Court's decision to cancel last month's disputed presidential election and order an early re-run.
 

"I never danced before but I'm dancing now. I even learned to like rap. This spirit will never die. Our nation is born," said Ludmila Volska, a piano teacher in her 40s from the western Ukrainian city of Kamenets-Podolsky. "But it's not finished yet. We will stand here to the end."

Her words were barely audible above the shouts of other protesters calling "Yushchenko, Yushchenko, Yushchenko".

The judges have given Mr Yushchenko everything he wanted when he filed his complaint alleging fraud in the election in which Viktor Yanukovich, prime minister and President Leonid Kuchma's candidate, was declared the official winner.

Mr Yushchenko wanted the vote cancelled and a re-run to be held as soon as possible. The court could have limited itself to cancelling the poll and leaving it to the politicians to set a new election timetable. But it went the whole way in Mr Yushchenko's favour in ordering a re-run within three weeks, that is by December 26.

Mr Yushchenko's headquarters welcomed the ruling as a victory for democracy. But the verdict is a bitter defeat for Mr Yanukovich, who faces a probable electoral thrashing if the new poll is carried out fairly. The ruling is also a humiliation for the authoritarian Mr Kuchma, who saw a Yanukovich presidency as the best way of retaining influence when he steps down after a decade in office.

Even before yesterday's ruling, Mr Kuchma was preparing to ditch Mr Yanukovich. Seeing a Yushchenko presidency as increasingly likely, Mr Kuchma has in recent days advocated wholesale political reforms that would transfer power from the president to parliament. Only then would new elections take place. Mr Kuchma wanted to make sure the presidency would be neutered before Mr Yushchenko took office.

Trying to retain power through parliament would be much harder for Mr Kuchma than running the country through the powerful presidential machine, but he would find it preferable to giving the keys to Mr Yushchenko.

That strategy now looks in tatters. But Mr Kuchma has enjoyed power for too long to give up easily. He still has a few cards to play. In theory, he could raise the political stakes by declaring a state of emergency and trying to delay the polls. But he would be obliged to secure parliamentary backing within three days - and the current divided parliament would be most unlikely to give such support.

Mr Kuchma could play tough over the conditions for the election re-run. Mr Yushchenko wants to make sure a new poll is free and fair - and has demanded that the government step down to make sure it cannot interfere, and that the Central Election Commission, which supervised the disputed poll and declared Mr Yanukovich the winner, be reconstituted.

Parliament has passed votes of no-confidence in both the government and the election commission, but it is the president who decides. There could still be some tough bargaining ahead.

The international implications of the judges' ruling are also significant. Russian President Vladimir Putin, who publicly supported Mr Kuchma's opposition to an early election re-run only this week, has been made to look foolish. European Union leaders who backed a rapid re-run, especially Polish President Aleksander Kwasniewski, will be more than satisfied.

However, EU officials will be careful not to crow too loudly. They will not want to add to Mr Putin's discomfort. And they will not want to take too much for granted until the polls are safely out of the way. International mediators headed by Javier Solana, the EU foreign policy chief, are due to visit Kiev in the next few days for another round of talks.

The election timing could be a problem. The court set December 26 as the latest date for the new poll. Using the full three weeks would allow the maximum time for election preparations. December 26 is an ordinary Sunday in mainly Christian Orthodox Ukraine, which celebrates Christmas later than the west.

But it would probably be the worst possible date for recruiting the thousands of international observers who will be required.