KIEV, Ukraine — Ukrainian ex-world boxing champion Vitali Klitschko has announced he will not run for president and will instead throw his support behind billionaire businessman Petro Poroshenko.

Klitschko told a congress of his UDAR party Saturday that he plans to run for mayor of the capital city, Kiev.

His endorsement will prove a valuable boost for Poroshenko, who played a prominent role in the protest movement that led to the toppling last month of President Viktor Yanukovych.

Poroshenko, the owner of a major confectionery company and a former foreign minister, already leads in the polls for the May 25 presidential election and is seen as likely to beat ex-Prime Minister Yulia Tymoshenko, who announced her candidacy this week.

The Kiev mayoral election is also scheduled for May 25.