The United States weighed into the two-man contest on Wednesday, one day ahead of Strauss-Kahn's interview with the IMF board.
US Treasury Secretary Henry Paulson urged the IMF Board to back the Frenchman as a replacement for Rodrigo Rato.
"The US is supporting Mr. Strauss-Kahn because we believe he will work to make the bold reforms necessary to lead a strong and relevant Fund into the future.
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Strauss-Kahn had already been widely seen as the favourite against Josef Tosovsky, a former Czech prime minister and central bank chief who was surprisingly nominated by Russia.
Rato is to step down after the 185-nation institution's annual meeting in late October.
The former Spanish finance minister announced in June he would leave nearly two years early, citing personal reasons.
The 24-member IMF executive board, which interviewed Tosovsky on Tuesday, will announce the results of a vote on September 28.
With 16.83 percent of the voting rights, the United States is the la