In this July 23, 2015, photo, Republican presidential candidate Wisconsin Gov. Scott Walker speaks at the American Legislative Exchange Council 42nd annual meeting in San Diego. Walker says the U.S. Environmental Protection Agency should become an "umbrella organization," with most of its powers shifted to state regulators. Walker discussed the idea in a story published Monday by the Washington Examiner and again with reporters following a campaign stop in Chicago. (AP Photo/Denis Poroy)MADISON, Wis. (AP) — Republican presidential candidate Scott Walker said Monday he would shift most of the responsibilities of the U.S. Environmental Protection Agency to state-based regulators, leaving the EPA to serve as an “umbrella organization” that would resolve disputes between them.