A Republican bill to repeal and replace ObamaCare is teetering on the edge of defeat.

FOX's Jared Halpern has more from Washington:

A major setback for a last-ditch repeal and replace bill. Arizona Republican John McCain has announced his opposition, writing in a statement he "cannot in good conscience vote for the Graham-Cassidy" proposal.

The bill authored by Republican Senators Lindsey Graham and Bill Cassidy is designed to shift a lot of health spending into block grants from states.

Kentucky's Rand Paul has also announced opposition. GOP leaders can afford only two Republican no votes. Maine's Susan Collins indicates she's leaning no and Alaska's Lisa Murkowski has expressed concerns.

In Washington, Jared Halpern, FOX News.

Follow Jared Halpern on Twitter: @JaredHalpern