The latest version of the American Health Care Act continued to leak GOP support on Tuesday, as Republicans stumbled to defend critical details of the bill that Democrats and outside groups have effectively defined as dangerous to sick consumers.

Michigan representative Fred Upton—a former chairman of the House Energy and Commerce Committee, which has jurisdiction over Obamacare repeal—was the latest and largest member to pull his backing. He opposes an amendment to the legislation that would conditionally allow states to waive a mandate banning insurers from determining premiums based on an individual's health status. "I've supported the practice of not allowing pre-existing conditions to be discriminated against from the very get-go," he told radio station WHTC. "This amendment torpedoes that, and I told leadership that I cannot support this bill with this provision in it."

Depending on the count, Upton is the twenty-first or twenty-second GOP member to pledge a no vote. If the party loses a twenty-third, the bill cannot pass, assuming the participation of every lawmaker and the guaranteed disapproval of every Democrat.

Most of the dissenting Republicans have echoed Upton—and characterizations from Democrats, several medical associations, and the mainstream press. The most extreme interpretation of the waiver amendment is an outright distortion of its language. "The new Trumpcare will allow states to decide whether or not insurers have to cover Americans with pre-existing conditions," Senate minority leader Chuck Schumer said in a floor speech. That is a lie: Under current law, insurers on the individual market must provide coverage to all comers, including those with a pre-existing medical condition, and no iteration of the AHCA would have changed the requirement.

The AARP has been fairer but still harsh in its assessment. An advocacy letter from the group said the bill would "end protections for 25 million Americans between 50-64 with preexisting conditions like cancer, heart disease, and diabetes." It's true that the legislation would allow states to opt out of protections as Obamacare wrote them. But only if those states replaced them with the protections provided for in the AHCA: high-risk pools, which include money that help pay costs incurred by pricier consumers. An AARP spokesman provided specificity to THE WEEKLY STANDARD about the association's position: It favors the ban on using health status in determining premiums and criticizes risk pools. "Prior to the [Affordable Care Act], high-risk pools provided skimpy coverage, charged exorbitant rates, or limited enrollment through waiting lists—making access to care unaffordable or unavailable to people who needed it."

Upton shares doubts about these pools; he told The Hill that funding them beyond the level contained in the bill "would not do the trick." Rep. Charlie Dent, a moderate Republican against the legislation, said likewise. The AHCA contains $10 billion over nine years that states can access for purposes like high-risk pools. A separate amendment added to the bill has $15 billion for a separate cost-containment program.

Little of the debate about the legislation has considered the merits of these ideas. Rather, it's focused on the Obamacare provisions they're designed to supplant. "I have always stated that one of the few good things about Obamacare is that people with pre-existing conditions would be covered," said Rep. Billy Long, a Missouri rank-and-filer who announced his surprise opposition to the AHCA on Monday.

But it's not such a shock considering the GOP's longstanding position on pre-existing conditions protections in the Obamacare replacement process. From the get-go, Republican leadership touted that its bill "prohibits health insurers from denying coverage or charging more money to patients based on pre-existing conditions." The latter part describes the effect of Obamacare's health status regulation, which was retained in the first version of the legislation. In a state permitted to waive it, people with a pre-existing condition who also fit other descriptions, like being off the market for an extended time, would doubtlessly face higher premiums relative to what they would under current law. But the purpose of risk pools and risk-sharing programs is to help offset the additional costs. In a state that uses them, the AHCA would still "prohibit health insurers from denying coverage"—and prevent patients from paying more money based on pre-existing conditions, the GOP would hope.

Avik Roy has noted the number of people this matter concerns; " Thanks To Democrats, Pre-Existing Conditions Outweigh The Uninsured In The GOP Obamacare Deal," he wrote last week. They weigh so much, in fact, they're on the verge of sinking the bill.