Former world champion boxer-turned-politician Vitali Klitschko bowed out of the race for Ukrainian president on Saturday, throwing his weight behind billionaire oligarch Petro Poroshenko, known as the “Chocolate King” for owning the country’s largest confectionary.

Instead, Klitschko said he would enter the Kiev mayoral race.

“The only chance to win is to nominate a single candidate from the democratic forces," Klitschko said Saturday. "Let’s leave the principle ‘two Ukrainians – three hetmans’ to other politicians. During the last year I had been insisting on nominating one candidate... It should be the candidate who has the greatest support of citizens. I offer the only candidate from the democratic forces Petro Poroshenko be supported in the presidential elections.”

“I have made the considered decision to run for Kyiv mayor,” Klitschko added. “I want to make Kyiv a really European capital, and we should do our country a truly European country. All the reforms and all initiatives start in the capital.”

Klitschko’s withdrawal, announced during a conference in Kiev of his Ukrainian Democratic Alliance party, whose acronym means “punch,” sets the stage for a showdown between two oligarchs: Poroshenko and Ukraine’s former Prime Minister Yulia Tymoshenko, dubbed the “Gas Princess” for the huge stake she has amassed in the natural gas industry.

#Klitschko endorses #Poroshenko for #Ukraine president, will run for #Kyiv mayor instead http://t.co/Gtv5qVU4VB pic.twitter.com/P311ySKFpP

— Christopher Miller (@ChristopherJM) March 29, 2014

Tymoshenko was released from prison on Feb. 22 after serving more than two years of a seven-year sentence for abuse of office. The case was widely viewed by the West as politically motivated.

The Ukrainian presidential and Kiev mayoral elections are scheduled for May 25.

Klitschko’s announcement came as a shock to many within his UDAR party. Bohdan Kisil, a party spokesperson, told Mashable he had not been notified beforehand that Klitschko would duck out of the contest. A party member, who spoke to Mashable on the condition of anonymity because he was told not to comment personally on the news, said many party officials were not privy to their leader’s decision before the conference.

More than 15 people have announced or are reported to be considering running for the Ukrainian presidency. Among them are seasoned politicians from deposed pro-Russian President Viktor Yanukovych’s Party of Regions, as well as members of civil society.

But it is Poroshenko who leads in most polls, with Klitschko in a distant second before his announcement that he will pull out and Tymoshenko in third place.

Tymoshenko: 'Language is not important for us, Ukraine is united thanks to Maidan and Putin' pic.twitter.com/v5ALZ8nJSN

— Maxim Eristavi (@MaximEristavi) March 29, 2014

Analysts believe she could now face pressure to withdraw from the race herself and back Poroshenko. In a news conference earlier this week, during which she announced her candidacy, she said she would support the chocolate baron should voters not elect her.

Klitschko had been the reigning World Boxing Council heavyweight champion when he gave up his belt to run for president. He rose to further prominence over the course of more than three months of anti-government protests known as Euromaidan that overthrew Yanukovych on Feb. 22. More than 100 people died during violent clashes between protesters and police during that time.

A supporter of European integration and a leader of the protest movement, Klitschko was seen then as Yanukovych’s chief competitor, eclipsing the ousted president in many polls. Throughout March, however, he has watched those numbers tumble.

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