He can lean toward conservatives like Rand Paul of Kentucky and Mike Lee of Utah, who want to dismantle as much of Obamacare as they possibly can. But if he does that, he risks losing a group of Senate moderates, including Susan Collins of Maine, Lisa Murkowski of Alaska, Rob Portman of Ohio and Shelley Moore Capito of West Virginia, who are pushing for a slower phase-out of the Medicaid expansion that is covering low-income people in some of their states.

The stakes are high: The GOP’s political identity is tied to the repeal pledge Republicans have made since the Affordable Care Act was signed more than seven years ago.