"We have withdrawn 26 parliamentary candidates in favor of the UDAR Party," the head of the central election headquarters of “United opposition”, Oleksandr Turchynov, said, according to the Interfax agency.
Ukraine is to hold crucial parliamentary elections on 28 October (see background).
The “United opposition” is made up of of former Prime Minister Yulia Tymoshenko Batkivschyna's supporters, and Arseniy Yatsenyuk's Front for change party.
Turchynov declined to name the candidates, but said that the electoral list would soon be made public, and includes current MPs.
"This decision was difficult, but it was taken. Moreover, I can say that we consider this process to be positive for Ukraine, as it strengthens the positions of democratic forces during this election campaign," Turchynov said.
Arseniy Yatsenyuk, leader of the council of “United opposition”, in turn said that the decision to withdraw 26 opposition candidates in favor of UDAR would significantly increase the opposition's chances of winning the elections.
On October 14, the UDAR Party decided to withdraw 26 of its candidates running for MP in single-member constituencies in favour of Batkivschyna candidates in order to maximise votes for the opposition.
The moves appear to indicate that UDAR and the “United opposition” are seeking to avoid past mistakes.
On a visit to Brussels last March, Klitschko said taht he had drawn lessons from the opposition's defeat in mayoral elections in Obukhiv, on 18 March. UDAR and Tymoshenko's party Batkivshchyna had separate candidates, and were beaten by President Viktor Yanukovich's Party of Regions.
Knock out punch
Klitschko is a former boxing world champion, who holds the second best knockout-to-fight ratio of any champion in heavyweight boxing history after Rocky Marciano.
Having recently ended his sporting career, he founded in April 2010 the political party UDAR, the Ukrainian Democratic Alliance for Reform, the acronym means "punch" in Russian and Ukrainian.
His Western-style liberal party has recently surged in popularity to second place behind the Party of Regions. Last week a survey gave UDAR 16% of the vote, behind the Regions with 23.3%. The “United Opposition” bloc, which includes Tymoshenko’s Batkivshchyna, had 15.1%.