* Colombia's Ocampo withdraws from World Bank contest
* U.S. nominee Jim Yong Kim likely winner
* Russia says it supports Kim
By Lesley Wroughton and Tiago Pariz
WASHINGTON/BRASILIA, April 13 (Reuters) - Former Colombian finance minister Jose Antonio Ocampo ended his bid to become World Bank president on Friday, leaving two candidates in an unprecedented challenge to U.S. control of the global development institution.
With the board of the World Bank to meet on Monday to pick a new president, Ocampo said he hoped emerging-market nations would rally behind Nigerian Finance Minister Ngozi Okonjo-Iweala in a race that he said had turned highly political.
Okonjo-Iweala, a former World Bank managing director, is now the sole candidate from developing nations in a race against U.S. nominee Jim Yong Kim, a Korean-American health expert who appears almost certain to secure the post.
Ocampo, who was nominated by Brazil, said his candidacy had been "handicapped" by a lack of support from his own country. Colombia said last month it was focusing on a bid for the presidency of the International Labor Organization, where it had a greater chance of success.
"It is clear that the process is shifting from a strict merit-based competition, in which my candidacy stood on strong grounds, into a more political-oriented exercise," he said in a statement.
"In this process, I stand on weaker grounds due to the lack of open support from the government of my home country, Colombia," he added.
Ocampo, now the director of economic and political development at Columbia University in New York, said he did not believe the selection process had been conducted in a fully open, transparent and merit-based fashion, but it had established a strong precedent.
However, his decision to leave the race does not mean all developing countries will support Okonjo-Iweala in a straw poll on Monday when the World Bank board tries to find consensus on a successor to Robert Zoellick, who is departing in June.
Indeed, the promise of a united front from emerging markets evaporated on Friday when Russia said it would support Kim, becoming the first major emerging economy to do so.
"Taking into account Mr. Kim's considerable professional qualities, as well as his experience and knowledge, the Russian Federation will support the candidacy of Jim Yong Kim during the voting by the bank's board of directors," the Russian Finance Ministry said in a statement.
Under a informal agreement, the World Bank has always been headed by an American and the International Monetary Fund by a European.
Emerging-market nations have been seeking to challenge U.S. leadership at the bank to increase their influence in global economic institutions long dominated by rich nations.
While Kim is still the favorite to win the World Bank presidency due to backing from the United States and European countries, a rigorous challenge from developing countries could put them in a stronger position to extract concessions.
It also increases their odds of winning senior jobs coming open in the next few months, including chief economist and head of the International Finance Corp, the World Bank's private-sector lending arm.
Okonjo-Iweala thanked Ocampo and said his presence had helped to further a shared goal of an open selection process.
"I am proud that Dr. Ocampo and I have helped make history by changing the way that World Bank presidential elections are contested," she said in a statement.