Say it ain't so, Mike.

Indiana Gov. Mike Pence was known as a stalwart fighter for limited government principles as a member of the House of Representatives (one of few Republicans to have voted against President Bush's Medicare prescription drug plan and No Child Left Behind law). But on Tuesday, he betrayed taxpayers when he embraced an expansion of Medicaid through President Obama's healthcare law.

Pence argues that his expansion of Medicaid is actually a victory for market-based principles because of concessions he won from the Obama administration providing the state more flexibility over the implementation of the program. But this is merely window dressing. Any plan that expands the Medicaid program imposes more costs on taxpayers, expands the federal role in healthcare and should be passionately opposed by those who care about the nation's future. The Congressional Budget Office, in its latest report, said that the federal government will be spending $920 billion over a decade expanding Medicaid through Obamacare.

As I wrote in May when Pence first proposed an alternative expansion, ultimately Pence buckled under pressure from hospital lobbyists who are eager to receive more federal money through the expansion.

The decision to expand Medicaid should damage Pence's prospects as a candidate for the 2016 Republican presidential nomination, as it will be harder for him to win back the trust of conservatives who he has already angered by his embrace of Common Core.

But the bigger problem is that Pence's decision to expand Medicaid could give cover for other Republican governors to do the same.

Myopic Republican governors think they can fool conservatives by gaining token concessions on what remains a government-run healthcare program and calling it "free market reform." But the Obama administration is playing the long game, realizing that if it keeps adding beneficiaries to the books, big government liberalism wins.

Should GOP Governors Agree To Obamacare's Medicaid Expansion? in Washington Examiner's Hangs on LockerDome