A new study recommends building a barrier or series of barriers to stop Asian carp and other aquatic invasive species from migrating into Lake Michigan from the Mississippi River basin through the Chicago Area Waterway System — and to prevent invasive species from migrating the opposite direction, as zebra mussels already have done.

An environmental coalition asked candidates to promise if elected to continue an Obama administration program dealing with some of the Great Lakes' most pressing environmental problems, including the invasive species, Asian carp.

TRAVERSE CITY, Mich. (AP) Environmental activists Tuesday challenged President Barack Obama and the Republicans hoping to unseat him to support a hotly debated plan to protect the Great Lakes from an Asian carp attack by cutting off their Chicago-area connection to the Mississippi River watershed.

Environmental activists Tuesday challenged President Barack Obama and the Republicans hoping to unseat him to support a hotly debated plan to protect the Great Lakes from an Asian carp attack by cutting off their Chicago-area connection to the Mississippi River watershed.