Congress should consider changing the mandate of the Federal Housing Finance Agency’s conservatorship of Fannie Mae and Freddie Mac to address a “conflict of interest” that inhibits the Finance Agency’s supervision of the GSEs, a housing economist told senators this week.Testifying before the Senate Committee on Banking, Housing and Urban Affairs, Columbia School of Business Professor Christopher Mayer said a significant problem with the ongoing operation of the GSEs has been the failure to adequately address operational conflicts.“The evidence suggests that the conflict of interest between the businesses of providing mortgage guarantees and managing a large retained portfolio of mortgages and [mortgage-backed securities] has led to obstacles to normal credit conditions,” said Mayer.