Ohio's Republican governor, John Kasich, ran for office as a limited-government conservative in 2010 and won. But that did not stop him this month from embracing one of the costliest provisions of President Obama's health care law -- its expansion of state Medicaid. Kasich's decision, along with those of several putatively conservative Republican governors such as Michigan's Rick Snyder, Arizona's Jan Brewer and North Dakota's Jack Dalrymple, demonstrates how difficult it is to stop the unchecked growth of government.

Obamacare's expansion of Medicaid has always been one of its most controversial elements. With Medicaid already squeezing state budgets across the country, governors in both parties feared that its expansion to as many as 18 million new beneficiaries would prove unsustainable. After some unpleasant horse-trading over Obamacare in late 2009 (recall the "Cornhusker Kickback"), the bill was changed so that the federal government will pay the whole cost of the expansion until 2020, and then 90 percent of it after that. This will cost federal taxpayers $932 billion over a decade if every state participates, or about 50 percent more than the tax hike on the wealthy that Obama secured at the beginning of this year.

Last year, 26 states won their lawsuit challenging the federal government's ability to coerce states into expanding the Medicaid program. This is what allowed Kasich a choice, and he chose big government. Kasich, a former congressman and House Budget Committee chairman during the Clinton-Gingrich government shutdown fights of the 1990s, rode the backlash against big government into the Ohio governor's mansion in 2010. A regular speaker at Tea Party rallies, Kasich boasted, "I think I was in the Tea Party before there was a Tea Party." Days before his election in 2010, he argued, "Obamacare must be blocked."

So why the volte-face? "It makes great sense for the state of Ohio because it will allow us to provide greater care with our own dollars," Kasich argued. The actual explanation for his embrace of the Medicaid expansion is purely political. Already chastened by his failed attempt at public-sector union reform and scared by Obama's victory in the state, Kasich faces re-election next year. Had he refused to expand the state's program, he would have faced an onslaught of political attacks that he was refusing to accept free money to care for poor Ohioans.

The end result is that a politician who ran for office claiming to have been "in the Tea Party before there was a Tea Party" is now actively embracing a policy that the Tea Party movement was specifically born to oppose. It comes as no surprise that governors with fewer conservative credentials would go and do the same thing.

This should serve as a sober reminder to conservatives: No matter how big a disaster Obamacare becomes when it's implemented next year, the nation is stuck with it, or at least with its costliest provisions. Big government takes root easily, and it is one of the most difficult weeds to remove.