Senate Republicans, who have promised a repeal of the Affordable Care Act for seven years, took a major step on Thursday toward that goal, unveiling a bill to cut Medicaid deeply and end the health law’s mandate that most Americans have health insurance.

Senate leaders on Wednesday were putting the final touches on legislation that would reshape a big piece of the U.S. health-care system by dramatically rolling back Medicaid while providing a softer landing to Americans who stand to lose coverage gained under the Affordable Care Act.

Sen. Dean Heller (R-NV) said Thursday that he has yet to make a decision on his support for the Senate’s bill to repeal Obamacare, but he said in a statement that he has “serious concerns” about how the legislation will impact those on Medicaid.

The first Republican governor who opted to expand Medicaid has decided that Nevada will not be the first state in the nation to attempt to open the government-subsidized health care program to anyone, regardless of need.

Centene Corp, one of the largest players in the Obamacare individual insurance market, said on Tuesday it would expand into three new states in 2018, despite uncertainty over the future of the legislation under President Donald Trump's administration.

The Trump administration has made critical ObamaCare subsidy payments to insurers for the month of June but won't provide any certainty about whether they'll continue in the future.