A former Obamacare chief read through the revised AHCA — and he has some grave concerns

Hours before House Republicans are set to pass the American Health Care Act, the man who ran the agency that administered much of the Affordable Care Act issued a dire warning.

Andy Slavitt, a former member of the Obama administration who helped clear up the  HealthCare.gov debacle and served as acting administrator for the Centers for Medicare and Medicaid Services, went on a tweet storm Wednesday night warning that the GOP's so-called "Obamacare repeal bill" could have negative impacts for Americans with pre-existing conditions.

On Wednesday, Rep. Fred Upton (R-Mich.) tacked on an amendment to the AHCA that he said would create an $8 billion fund to offset potential cost increases for people with pre-existing conditions. 

The amendment was needed because the AHCA would allow states to waive a rule that requires insurance companies to charge people in the same age group and geographical area the same amount for insurance — regardless of whether they have pre-existing conditions. Upton hoped his amendment would win back votes from Republicans who were wary the AHCA would negatively impact sick Americans.

Yet according to Slavitt, the $8 billion fund is not only not enough to take care of all of the people who will potentially see cost increases because of the waivers, there's also nothing in the amendment text that requires the money be spent on people with pre-existing conditions.

"This $8B targeted to take care of ppl w pre-existing conditions ... doesn't have to be used for ppl w pre-existing conditions," Slavitt tweeted. "The number of times the words 'pre-existing conditions' are used in the bill ... Is ZERO."

Upton himself even admitted the fund might not be enough to cover everyone facing increases thanks to their pre-existing conditions.

And a study from the left-leaning Center for American Progress found that the $8 billion would only help a fraction of Americans classified as having pre-existing conditions.

"The provision would subsidize health care for only about 76,000 more individuals out of the millions with pre-existing conditions," CAP said in a news release Wednesday. "If used toward high-risk pools, the $8 billion over five years promised in the amendment would fill in only 4% of the gap in funding to sustain the pools."

Nevertheless, House Republicans will vote on the legislation on Thursday — with leadership guaranteeing the bill will pass.