TRAVERSE CITY, Mich. - U.S. attorneys general in the Great Lakes region want a multi-state campaign to cut an artificial link between the Great Lakes and Mississippi River watersheds that provides a pathway for invasive species.

In a letter obtained by The Associated Press, the attorneys general invite their counterparts in 27 other states to pressure the U.S. Army Corps of Engineers for quicker action.

The Corps is studying whether to separate the drainage basins in the Chicago area, where they were joined more than a century ago by construction of a canal. Zebra and quagga mussels have used the waterway to invade states farther south, and the Asian carp is threatening to migrate into the Great Lakes.

The Corps report is due in 2015. The letter demands a faster timetable.