The Republican fight against Medicaid expansion is far from over, but there are fewer opponents than there used to be.

The expansion of the government health insurance program was originally supposed to be mandatory under the Affordable Care Act, but the Supreme Court made it optional as part of a landmark decision on the law in June of 2012.

In the wake of the decision, Republican governors flocked to announce they were declining to expand coverage.

As of 2014, 19 states — 18 of which are led by Republican governors — have declined outright to expand coverage, but some former holdouts are beginning to come to terms with expansion.

This week, Pennsylvania formally agreed to terms with federal regulators, raising the number of states that have expanded coverage for low-income residents under Obamacare to 27. Pennsylvania is the ninth state led by a Republican governor to expand Medicaid.

Another Republican, Tennessee Gov. Bill Haslam, also announced Friday that his state will begin the process of preparing a plan for Medicaid expansion.

The state is expected to pursue a hybrid plan to help lower-income residents enroll in plans on the Obamacare exchanges.

Tennessee joins Utah and Indiana in the pool of states where Republican governors are actively negotiating with the Obama administration to expand coverage, and more states could be joining the pool soon.

Democratic governors in Missouri and Virginia are on record for supporting expansion, but have have failed to persuade their respective legislatures to go along.

Florida Republican Gov. Rick Scott has indicated a willingness, with some serious caveats, to expand coverage if he can persuade his legislature. Scott's Democratic challenger, former Republican Charlie Crist, has threatened to use the line-item veto to push through an expansion if elected.

In Georgia, Democratic gubernatorial candidate Jason Carter was briefly neck-in-neck with Republican Gov. Nathan Deal, although he's trailed off in recent weeks. Carter is on record for expansion.

And in Wyoming, Republican Gov. Matt Mead announced last week he had met with Obama administration officials to discuss potential terms for Medicaid expansion. He'll reportedly brief state legislators on the details in the new year.

The largest state to decline expansion, Texas, is unlikely to change its tune any time soon, and North Carolina's gubernatorial race isn't until 2016. There are still over 4 million people who would be covered but are not because of states declining the expansion.

Still, the trend is quite clear: Red states are gradually accepting Obamacare, and no states are reversing their decisions.