Shortly after House Republicans passed their revised bill to repeal and replace Obamacare on Thursday afternoon, Sen. Rob Portman (R-OH) said that the legislation would need major changes before he could pledge his support.

His statement goes to show that while the repeal bill passed the House with a razor-thin margin, it faces an uphill battle in the Senate.

“Congress must take responsible action that lowers health care costs, but these changes must be made in a way that does not leave people behind,” he said in a statement.

The Republican senator cited concerns that his constituents would lose their Medicaid coverage under the American Health Care Act.

“I’ve already made clear that I don’t support the House bill as currently constructed because I continue to have concerns that this bill does not do enough to protect Ohio’s Medicaid expansion population, especially those who are receiving treatment for heroin and prescription drug abuse,” the statement continued. “We have an opioid crisis in this country, and I’m going to continue to work with my colleagues on solutions that ensure that those who are impacted by this epidemic can continue to receive treatment.”