Sen. Lindsey Graham Lindsey Olin GrahamSenate Republicans signal openness to working with Biden Loeffler calls for hearing in wake of Netflix's 'Cuties' Quinnipiac poll shows Graham, Harrison tied in South Carolina Senate race MORE (R-S.C.) is firing a warning shot over a GOP ObamaCare replacement bill scheduled to get a vote in the House later Thursday.

"A bill — finalized yesterday, has not been scored, amendments not allowed, and 3 hours final debate — should be viewed with caution," Graham said on Twitter.

He added that while he was glad the House was making "apparent progress" on repealing and replacing ObamaCare, he is "concerned" about how it's going.

I appreciate the apparent progress on health care reform in the House of Representatives. I will admit, I’m concerned with the process. — Lindsey Graham (@LindseyGrahamSC) May 4, 2017

Graham's tweet comes as the House is racing toward a vote on the health bill, known as the American Health Care Act.

After weeks of behind-the-scenes negotiations, House GOP leadership appeared confident that it has the votes to pass the bill on Thursday.

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They are not expected to get a Congressional Budget Office (CBO) score in time, which would detail how many Americans could lose their health insurance and the costs of the bill, ahead of the vote.

If it passes the House, it will head over to the Senate, where it is expected to undergo significant changes

"When they send it over here, it'll be a real big challenge on the Senate side as well, and you'll have an update of lots of stories about the discussions as we move towards trying to achieve that," he told reporters.

Senate leadership has a narrow path for passing the legislation. Republicans have a 52-seat majority and will need a simple majority to pass it under the special budget rules being used for the bill.

Several GOP senators came out against an initial bill that was pulled from the House floor in March after it became clear that leadership did not have the votes to pass the legislation.

GOP senators are particularly concerned about the Medicaid provisions and what will happen in states that expanded the program under ObamaCare, as well as new changes regarding coverage for those with pre-existing conditions.