Which GOP candidates are true reformers and which are just paying lip service to reform?

Precisely because there’s real money on the table, they are places where being a reformer requires more than lip service. One reason issues like immigration and education are appealing to Republican politicians looking to change their party’s image is that policy change in these areas seems relatively cheap — more green cards here, new curricular standards there, and nothing that requires donors and interest groups to part with their favorite subsidies and tax breaks.

But you can’t reform the tax code or health care that easily, which is why those issues offer better, tougher tests of whether a would-be conservative reformer should be taken seriously.

Not coincidentally, they’re policy tests that Obama-era Republicans have often conspicuously failed. On taxes, the party has been enamored of reforms — some plausible, some fanciful — that would cut taxes at the top while delivering little, or even higher taxes, to most taxpayers. (It’s an odd position for a party that is officially anti-tax to take in an age of wage stagnation, but at least the donors have been happy.) On health care, the G.O.P. has profited from the unpopularity of Obamacare, but we are now at Year 6 and counting without anything more than the pretense of a conservative alternative.