Representative Fred Upton helped guide dozens of Obamacare repeal measures through the House in recent years, but he has deep reservations about the GOP’s current bill.

“I’m not comfortable with it and I told the leadership that,” he said Friday, in a vivid illustration of the continuing obstacles to the GOP effort to resurrect its stalled repeal plan.

Until five months ago, Upton, a Michigan Republican, chaired the Energy and Commerce Committee, which has jurisdiction over much of health care policy. Now, he’s not ready to support the current bill and said the most recent revisions have made it worse.

Skepticism from Upton and other Republican moderates led GOP leaders to abandon an effort to hold a vote on the bill this week. Leaders say they’re still hopeful it can be passed next week.