A new GAO report gives us the magic number:

Since 2001, we reported that the United States had maintained nearly 70 legislative mandates prescribing U.S. policy goals at the IMF. These mandates covered a wide range of policies, including policies regarding combating terrorism, human rights, international trade, and weapons proliferation....

The mandates date from 1945 to 2005, with the majority enacted in the last decade. Some mandates address multiple policy issues, sometimes overlapping each other.

Click on the report to see the specific mandates. Most of them are perfectly unobjectionable -- but with this many constraints, it's a miracle that Treasury can keep track of them all, much less comply with them. Plus, the aggregation of hard constraints makes it difficult for the U.S. to have the policy flexibility that makes it easier to lead the institution.

Not surprisingly, the executive branch would like a little more latitude. In their response to the GAO, Treasury said:

As noted in the past, the extensive mandates tend to undermine our effectiveness in influencing the IMF. We would welcome efforts by the Congress to effect a consolidation of the legislative provisions to remove unnecssary mandates.

Full disclosure: the author of Treasury's response was one of my bosses when I worked there.