Illinoisans — particularly the state’s most needy — could be among those worst hit by the Republicans’ plan to overhaul the Affordable Care Act.

That’s according to a man with a rare perspective: Joel Shalowitz is both a medical doctor and has an MBA, with expertise in American health industry management.

“In Illinois, we are not in such hot financial shape,” said Shalowitz, a professor of preventive medicine at Northwestern University’s Feinberg School of Medicine, referring to the state’s much-publicized budget woes. “If we don’t get as much money for Medicaid as we previously received, and the state [of Illinois] wants to keep the number of eligible people who are covered, then we are going to have to come up with more money. Neither I nor anyone else really know where that’s going to come from.”

Illinois legislators could be faced with the politically dangerous task of raising the state income tax to help fund Medicaid, the federal-state program that serves low-income people, Shalowitz said. Approximately 3 million people in Illinois are enrolled in the program, with about 650,000 of those added to the rolls during the Medicaid expansion under the law, also known as Obamacare.

Aiming to reduce the role of government in health care, the GOP plan would repeal unpopular fines that President Barack Obama’s law imposes on people who don’t carry health insurance. It would replace income-based subsidies, which the law provides to help millions of people pay premiums, with aged-based tax credits that may be skimpier for people with low incomes. Those payments would phase out for higher-earning people.

In states that participated in the expansion, the Republican legislation would shrink the number of people eligible for Medicaid coverage and require states to drop people from coverage or risk incurring huge costs rapidly to keep them enrolled.

“We continue to review the proposal introduced in the U.S. House Monday to see how it will impact both our Medicaid population and consumers facing exorbitantly high insurance rates, and continue to emphasize that any change should be thoughtful and fair to the people of Illinois,” Eleni Demertzis, a spokeswoman for Gov. Bruce Rauner, said in a statement Wednesday.

If the state wants to maintain the numbers currently enrolled in Medicaid — and legislators don’t want to raise taxes — services might have to be cut, Shalowitz said.

The drop in federal money could then have a ripple effect, prompting doctors in Illinois to be less likely to accept Medicaid patients due to lower reimbursement rates. Hospitals could also suffer, particularly those that previously received subsidies to treat the poor — subsidies that went away when lower-income people got health insurance through Obamacare.

“It’s the worst of all possible worlds” for those hospitals, Shalowitz said. “They could be in very serious financial jeopardy.”

But Shalowitz says there’s enough dissension among congressional Republicans to suggest the House bill will be re-tooled.

“As it appears currently, there are enough Republicans opposed to this proposal that it doesn’t look like it’s going to pass in its current form,” Shalowitz said. “But anything can happen. You never know what kind of arm-twisting is going to occur or what political favors are going to be offered.”

Contributing: Associated Press