PORTLAND, Maine (AP) - The U.S. Senate has passed a proposal backed by Maine's senators to provide more care for military veterans who were exposed to toxic substances.

Republican Sen. Susan Collins and independent Sen. Angus King were among the supporters of the proposal, which is commonly called the "PACT Act." The proposal easily passed the Senate in mid-June.

The proposal is designed to expand U.S. Department of Veterans Affairs health care eligibility to post-Sept. 11, 2001, combat veterans. That includes more than 3.5 million veterans who have been exposed to toxic substances, Collins said.

The proposal would also create a framework for how to deal with future cases of service-connected toxic exposure. It would also expand presumptions related to exposure to Agent Orange, among other changes.

Collins said the proposal "puts us on the path to fulfilling the enormous debt we owe these veterans by expanding critical research on toxic exposure and providing relief to toxic-exposed veterans who may be experiencing serious illnesses and debilitating symptoms."

Republican Sen. Jerry Moran of Kansas and Democratic Sen. Jon Tester of Montana negotiated the legislation in the Senate.