Preliminary results put incumbent Kyiv Mayor Leonid Chernovetskyy clearly in the lead with almost 37 percent of ballots. The Chernovetskyy Bloc is also leading in the city council vote.
His reelection would be a blow to Prime Minister Yulia Tymoshenko, who secured a parliamentary vote in March to oust Chernovetskyy in connection with what she alleged were illegal land deals.
The early results are also bad news for the fiery prime minister because her preferred candidate, Oleksandr Turchynov, trails Chernovetskyy with under 19 percent in a vote largely seen as a dress rehearsal for the next presidential election in early 2010.
"The Kyiv elections are a serious electoral, psychological, symbolic defeat for Yulia Tymoshenko and her bloc," says Vadym Karasiov, who heads the Kyiv-based Global Strategic Institute, a think tank viewed as close to President Viktor Yushchenko. "She initiated the elections; she thought that in these elections she would get the capital's resources, Chernovetskyy would be removed, she would reformat the city council. As it turns out, having initiated the elections, she lost them and this means a lot of voters and many of the political elite will have doubts about the political possibilities of Yulia Tymoshenko."
Karasiov adds that "her charisma is now going to be doubted because, so far, that charisma has never been doubted and it has never let her down."
Other candidates linked to the democrats who swept to power during the 2005 Orange Revolution didn't fare much better, according to preliminary showings.
Former world boxing champion Vitaliy Klychko of the pro-Western PORA-PRP group garnered almost 18 percent of the vote, while Mykola Katerynchuk, an ally of Yushchenko, is credited so far with just over 4 percent.
The fact that Tymoshenko and Yushchenko backed different candidates highlights enduring divisions within the so-called Orange camp. The two former allies fell out shortly after coming to power, the dispute culminating with Yushchenko sacking Tymoshenko as prime minister in 2005.
The president reinstated her in December after their respective parties won a slim majority in parliamentary elections, but the governing coalition remains fragile. Tymoshenko recently accused Yushchenko of seeking to weaken her standing ahead of next year's presidential election.
Ihor Zhdanov, an independent political analyst, tells RFE/RL's Ukrainian Service that pro-Orange forces could have won the vote had they put differences aside and fielded a single candidate.
"The results of these elections simply confirmed Mr. Chernovetskyy's mayoralty. At the same time, two candidates from the democratic camp, Oleksandr Turchynov and Vitaliy Klychko, together received more votes than Chernovetskyy. What does this mean? It means that had the democratic camp had a single candidate, if people had been able to overcome their ambitions, then they would have had a victory and the mayor of Kyiv would be a representative of the democratic forces. This is the No. 1 conclusion of these elections: that politicians need to curb their ambitions, learn to agree and understand their responsibility to the voters."
But for now, pro-Western forces will have to put up with Chernovetskyy for another mayoral term.
A billionaire and former lawmaker, Chernovetskyy is known for his quirky behavior and often incoherent remarks.
"Who is the mayor today?" he once posed aloud. "Me, it's definitely me. And was there someone before me? I don't remember. I don't think there was anyone."
His political career is marked with controversy. Both he and his wife, for instance, avoided manslaughter convictions after killing two people in separate road accidents.
Chernovetskyy has also raised eyebrows with proposals such as forcing subordinates to undergo lie-detector tests, or with his support for an evangelical church headed by a controversial African minister.
In January, Chernovetskyy made the headlines with his scuffle with Interior Minister Yuriy Lutsenko, whom he accused of punching him in the face and groin after an argument. Lutsenko admitted slapping Chernovetskyy's face but claimed the mayor initiated the fight by kicking him in the knee.
RFE/RL's Ukrainian Service contributed to this story