By Malcolm Haslett
BBC Eurasia analyst
Ukrainian Prime Minister Viktor Yanukovych, declared the loser in Sunday's repeated presidential poll, has said he will never accept that he was defeated fairly.
On Wednesday he officially contested the result and has vowed to fight on to overturn the result.
But if his opponent Viktor Yushchenko and his supporters can overturn a declared election result, why not Mr Yanukovych?
Viktor Yanukovych has most support in eastern Ukraine
He still, after all, holds some cards. Technically, he is still prime minister. Though the Ukrainian parliament passed a vote of "no confidence" in his government on 1 December, incumbent president Leonid Kuchma - Mr Yanukovych's principal backer - refused to sign the final decree which would have dismissed him.
Now that Mr Yanukovych is attempting to pick up the reins of power, however, his opponents have repeated their calls for him to resign. Yushchenko supporters also prevented Mr Yanukovych from holding a cabinet meeting on Wednesday by blockading the government building.
Mr Yanukovych's other main assets are his strong support in the east of the country, and from Russia. He will undoubtedly try to play these cards in his efforts to cling on to power.
Already Mr Yanukovych has filed complaints to the Supreme Court contesting the validity of the repeat 26 December vote. In an attempt to underline the seriousness of his case he has contested the result in every one of the 225 constituencies in the country.
Yet Mr Yanukovych faces a formidable task. He lacks some of the key advantages enjoyed by his rival after the first rounds of voting. One is the credibility of the numbers.
In the first run-off between the two rivals, the official verdict - which gave victory to Mr Yanukovych - contradicted all the exit polls conducted by Ukrainian organisations. The claims of fraud were upheld by the Supreme Court.
Perhaps the most ominous sign for Mr Yanukovych is the apparent erosion of support for him among previous allies
The chairman of the electoral commission which had declared Mr Yanukovych victor then resigned. The first election was also strongly condemned by international observers from the OSCE for widespread and serious abuse.
The repeated vote, in contrast, was declared largely fair by the huge contingent of international observers. It is also unfortunate for Mr Yanukovych that his main areas of support are far from the capital, Kiev.
Protest demonstrations in eastern Donetsk, however widely seen through the world, do not have quite the same effect as the displays of indignation mounted by Mr Yushchenko's followers in the capital.
Mr Yanukovych and his camp have also lost their tight grip on the Ukrainian broadcast media, which they were able to manipulate quite blatantly before the first vote and for some days afterwards.
The first few days of the pro-Yushchenko protests in Kiev, for example, were not shown by the two main, government-controlled TV stations. But perhaps the most ominous sign for Mr Yanukovych is the apparent erosion of support for him among previous allies.
Several members of his own government, including first deputy prime minister, Mykola Azarov, are reported by agencies as declaring last Sunday's vote as free and fair.
And in Russia, some sections of the media previously on Mr Yanukovych's side, like the pro-government daily Izvestia, now seem ready to accept Mr Yushchenko as the future Ukrainian president.