The decision, expected Tuesday, could force new elections.
Tens of thousands of supporters of opposition candidate Viktor Yushchenko have rallied in the center of the capital, Kiev, since the government announced the results giving Prime Minister Viktor Yanukovich 49 percent of the vote to 46 percent for Yushchenko.
Yushchenko's camp claims that several surveys of voters at polling places gave their candidate as much as an 11-point lead and that there is evidence of inflated voter turnout, voters casting multiple ballots, intimidation of election officials and observers, coercion of students and public sector workers, inaccurate voter lists and destruction of some pro-Yushchenko ballots.
Ukrainian law requires that the Supreme Court consider complaints from individual precincts rather than rule on the validity of the election as a whole. To support its appeal, the opposition is focusing on results in eight southern and eastern regions that accounted for 15.35 million votes, more than half the 30.51 million votes cast.
Meanwhile, the departing Ukrainian president, Leonid Kuchma, said that he favored new elections if they would end the political stalemate that is threatening to destabilize the former Soviet republic.
"If we really want to preserve peace and consensus and build this just democratic society," Mr. Kuchma said in a statement, "let us have new elections."
Prime Minister Yanukovich also agreed to hold a new vote in the country's two eastern regions if the court finds that mass fraud took place.
"If there is proof of cheating, that something illegal occurred there and if there is no doubt among experts, I will agree with such a decision," Yanukovich said on national television.
Yanukovich was dealt another blow Monday when his campaign minister resigned, also stepping down as the country's central banker. Sergei Tihipko, who is also head of the Ukraine Workers Party, said at a news conference that the country was divided and that a new election was needed.
"We understand this has to be corrected. I am sure there is still time to rectify the situation, assuming the authorities will make the right decision without delay," he said Monday.
While Western media reports thus far have focused on the dramatic show of support for the opposition, the country's eastern region, which has closer cultural, linguistic and political ties to Russia, is threatening action if the election results are reversed.
As many as 3,500 officials from 17 regions convened an informal congress Monday and voted unanimously to seek autonomy by public referendum if the opposition continues its quest to make Yushchenko president, The New York Times reported.
The regional parliament in Donetsk voted 156-1 to begin publishing ballots for a referendum in the region as soon as this week.
In Washington, Secretary of State Colin Powell said that he had spoken by telephone to President Kuchma, and told him that it was important to keep the country intact.
"If we can keep things calm and allow the leaders and the politicians and members of the international community who are trying to help the Ukrainians all come together then, hopefully, a peaceful solution will be found," Powell told reporters.
The Bush administration has already said that it could not accept the results of the election.