Three Republicans have announced they will block a motion to proceed on a bill to repeal most of Obamacare, dooming a last-minute plan by Majority Leader Mitch McConnell to try to move ahead on efforts to replace the troubled healthcare law.

Sens. Shelley Moore Capito of West Virginia, Susan Collins of Maine, and Lisa Murkowski of Alaska have all declared they will not vote in favor of a bill that would repeal most of Obamacare after two years.