Developing countries want to end the cosy post-World War II arrangement under which the World Bank would always be headed by an American and the IMF by an European. Both the Europeans and Americans have agreed that they should stick to that informal agreement and keep developing countries out of the top positions.
However, European nations have been split between Rato and France's Jean Lemierre, head of the European Bank for reconstruction and development.
The US had been neutral in this argument among Europeans but the Wall Street Journal said, now it "is quietly trying to line up support globally for Mr Rato."
US officials, the paper noted, have not publicly expressed a preference for either of the Europeans in the race to succeed Horst Kohler as the IMF's managing director. Kohler resigned to stand for the presidency of Germany.
European Union finance ministers, said the Journal, recently turned to the US, the IMF's largest shareholder, and the rest of the international community for their opinion on the two men.
"By working quietly, the US hopes to avoid a confrontation similar to the situation that developed in 2000 when the US rejected Europe's top candidate," the paper said.
European countries, the Journal noted, "historically choose the IMF head, with US approval, while the US picks the president of the World Bank."
Rodrigo Rato was born in Madrid on March 18, 1949. His father was a real estate promoter and owner of a radio network, while his mother came from a family of wealthy Asturian mining magnates.
A graduate in Law, with a Masters in Business Administration from the University of California at Berkeley, he became well known to Spaniards as spokesman in parliament for the Partido Popular and later as finance minister.