Illinois Senator Dick Durbin is urging President Bush to move quickly to fill a leadership vacancy at the Midwest regional office of the Environmental Protection Agency.

In a letter to Bush, Durbin says Mary Gade's removal makes it appear as if the EPA is putting the interests of "big polluters" ahead of the environment.

Gade was regional administrator of EPA Region 5 until her resignation on Thursday. She claims she's being let go because her office was too aggressive in going after Dow Chemical to clean contaminated waters near its Michigan headquarters.

Gade told the Chicago Tribune she resigned after top EPA officials told her to quit or be fired by June 1st.

An EPA spokesman confirmed that she's been placed on administrative leave but declined further comment.