Associated Press

OKLAHOMA CITY -- U.S. Rep. John Sullivan is calling for the resignation of Treasury Secretary Tim Geithner following the downgrade of the nation's credit rating.

Sullivan joined fellow Republicans Allen West, Representative of Florida, and Bill Shuster, Representative of Pennsylvania, in sending a letter Thursday to President Obama asking for Geithner's immediate resignation.

The letter refers to Geithner as the "architect of a failed economic policy."

The three Republicans also blame Geithner for his assurances that the country was not in danger of losing its AAA credit rating.

Sullivan voted for the bill to increase the nation's debt ceiling and avoid a first-ever government default. After the bill passed, the U.S. credit rating was downgraded one notch from AAA to AA-plus by Standard & Poor's.