House leaders are still a few lawmakers short of getting the votes they need for the American Health Care Act, though they are within striking distance based on public whip counts and my own reporting. But they just lost a big vote.

Rep. Fred Upton of Michigan, who until January had been chair of the House Energy and Commerce Committee, one of the main health care legislating committees in Congress, officially came out against the bill on Tuesday.

Upton made the announcement during a local radio interview, and his office confirmed to me that he is a “no” vote on the bill.

This Upton quote gets at the crux of the GOP’s health care woes. The party just doesn’t agree on what goals of repeal and replace are. pic.twitter.com/5vEgP0eArK — Sarah Kliff (@sarahkliff) May 2, 2017

Upton had said late last week that he was uncomfortable with changes to the bill that won over the conservative House Freedom Caucus. Those changes would allow states to opt out of some of Obamacare’s insurance rules, which prohibited insurers from charging sick people more than healthy people and required plans to offer more comprehensive coverage — changes that potentially mean even more people would lose insurance than the 24 million estimated under the previous version of the bill.

A number of moderates have balked at those changes, arguing that they undermine promises Republicans and President Donald Trump have made to protect people with preexisting medical conditions.

House leaders and conservatives have argued that the bill still provides protections, only allowing states to opt out of those rules if they establish a high-risk pool where sick people could buy coverage. But that argument hasn’t persuaded Upton or many other moderates so far.

Here’s what Upton told Bloomberg last week:

Upton, for example, said his main concern is how those revisions affect coverage for people with pre-existing medical conditions. “The issue is potential higher costs to those with pre-existing illnesses," he said. "They’re trying to say that they still maintain access with continuous coverage but the question is what happens on the costs side of the thing.”

Upton had been the co-author of previous Obamacare repeal-and-replace plans. He has also helped author other major health care legislation, including a bill that overhauled Medicare payments to doctors and the 21st Century Cures Act, which sought to speed up drug approvals and medical innovation. Losing him means the latest push toward a repeal bill may be doomed yet again.