Here are two facts about New Jersey Governor Chris Christie. He is tremendously popular, with an approval rating in the mid-70s. And lots of national conservatives feel betrayed by him. These facts are closely related, and they reflect why Republicans are unlikely to heed calls to change their doomed economic policy agenda.

Christie is so popular for largely the same reasons that conservatives nationally have soured on him. He has charted a politically smart course, pushing conservative initiatives when they are popular and serve the interests of his state's residents. He hasn't been willing to die on every Tea Party hill.

Here are some of Christie's sins against conservatism: Today, he announced that New Jersey will accept Medicaid expansion dollars. In October, he praised President Barack Obama's handling of Hurricane Sandy recovery. In January, he excoriated Speaker John Boehner for recessing the House without passing a disaster relief bill. He refused to join the lawsuit seeking to overturn the Patient Protection and Affordable Care Act. He denounced Shariah law obsessives in the Republican Party as "crazies."

And so Christie hasn't been invited to speak at next month's Conservative Political Action Conference, a bizarre snub for one of the highest-profile and most popular Republican elected officials in the U.S. A CPAC insider tells National Review the conference organizers are upset about Christie's mixed stance on gun control. "Christie, the source adds, is simply not a conservative in the eyes of organizers," National Review reports.

But think about what conservative purists want from Christie. They would like him to take policy courses that would be not only unpopular but unpopular because they would disserve the interests of New Jersey residents. Declining the Medicaid expansion would have meant refusing to accept money from a federal program that New Jersey taxpayers would finance regardless of Christie's actions. Not turning the screws on Boehner would have meant New Jersey getting less relief money, or getting it later.

It's not that Christie is a liberal. He pushed through reforms that save money by reducing the generosity of health and pension benefits for public employees. He insisted on allowing an income tax increase on high earners, enacted under his predecessor, to sunset, leaving New Jersey with a top rate of "only" 8.93 percent. He killed a Hudson River rail tunnel project, beloved by the left, because it was engineered to be too expensive and had too high a risk of cost overruns. He capped increases in local property taxes.

More generally, Christie has made the case that New Jersey's public expenditures are unusually and unnecessarily high and that spending restraint, not tax increases, is the answer to the state's fiscal problems. That message is popular because, in New Jersey, it happens to be true.

What's clear from Christie's eclectic record is that he's not starting from a broad ideological principle like "government should be small" and working down. He is trying, on a case-by-case basis, to find policies that will be popular and serve his state's residents well. This doesn't always work (Christie's bailout of the Revel casino is a good example of a policy choice that was politically expedient but substantively unwise) but on the whole it has been a pretty good approach to governance.

It's no coincidence that Christie has ended up in the same place on so many policy questions as New York Governor Andrew Cuomo, despite their difference in party. Cuomo is a Democrat who has been willing to ditch liberal ideology when doing so is popular and serves New York's fiscal interests. Like Christie, Cuomo has sought and received cost-reducing pension reforms and capped property taxes. Like Christie, Cuomo has an uneven relationship with organized labor. And like Christie, Cuomo is viewed by a lot of the more ideologically pure members of his party as a traitor.

What so bothers conservatives about Christie is that he has figured out which parts of conservatism are working and been willing to ditch the ones that aren't. His Ronald Reagan Presidential Library speech in 2011, full of explicit criticism of Obama, also contained an implicit critique of congressional Republicans' scorched-earth opposition to the president. Christie has often intimated that as president, as in his governorship, he would treat compromise with the other party as an important strategy rather than a dirty word.

So maybe the CPAC insider is right that Christie isn't a conservative, at least as conservatives in the U.S. today define themselves. The insider told National Review that Christie has a limited future in the Republican Party because of his apostasy. But Christie is only an apostate because he realizes that conservatism, as defined by the sort of people who organize CPAC, has a limited future in America.

(Josh Barro is lead writer for the Ticker. E-mail him at jbarro1@bloomberg.net and follow him on Twitter.)