At present, the Republican presidential campaigns opposing Newt Gingrich must look at the unlikely front-runner as something of a piñata: a big, fat target ready to explode, showering votes on his rivals, once it is decided which angle offers the most decisive blow. There are plenty of ripe lines of attack, most notably Gingrich’s endless flip-flopping on global climate change punctuated by his notorious 2007 ad with Nancy Pelosi. His record of support for an individual mandate to purchase health insurance should also be tempting to opponents, given the issue’s prominence in the news as the Supreme Court prepares to rule on its constitutionality. And though personal attacks are always trickier, you’d figure rivals could find some way to remind the Christian Right leaders who are toying with a Gingrich endorsement that this thrice-married, twice-converted man is hardly a convincing champion of godly behavior.

Of all these possible avenues, however, it is truly a sign of the times that the angle of attack most are choosing is Newt’s recent position on immigration. We have been monotonously told that this election is about the economy and the federal budget, not social issues, and in any event Republicans understand the general election risk of alienating Hispanic voters. But with the smoking ruins of Rick Perry’s candidacy still on display, it’s far past time to reassess both of those assumptions: Immigration remains a key issue to millions of Republican caucus and primary voters—in spite of, not because of, the economy—and they will not accept candidates taking the “wrong” position on the matter for the sake of electability.

Any analysis of this issue must begin with the understanding that immigration is a black-and-white moral challenge to a majority of conservative activists. It’s not the product of some recession-related anxiety about immigrants taking jobs; indeed, in many parts of the country (particularly in the South), the Hispanic presence in the economy and in the population has visibly diminished during the last couple of years. Accordingly, recent conservative immigrant-bashing has been focused not on undocumented workers taking away jobs, but on their families’ alleged dependence on welfare (the main issue in California’s famous Proposition 187 debate during the 1990s) and on their alleged collective conspiracy to use “anchor babies” born in the United States to colonize the country with large families living off the public-assistance fat of the land. That is why Perry’s stubborn defense of public educational subsidies for the children of undocumented workers struck such a powerfully destructive chord with Tea Partiers.

Moreover, a big inspiration behind the Tea Party has been a revolt of movement conservatives against Republican politicians who were willing to bend public policy and spend taxpayer dollars to curry favor with select target constituencies—you know, like Democrats do. It was not lost on conservatives that the Bush-McCain commitment to “comprehensive immigration reform” was central to Karl Rove’s strategy of adding at least a robust minority of Hispanic voters (along with seniors seduced by the Medicare Rx drug benefit and married women attracted to No Child Left Behind) to the party’s base to forge a durable majority. To hard-core conservatives, these abandonments of conservative principle were both morally and politically abominable, locking the GOP into an unwinnable vote-buying competition with the hated socialist enemy at the expense of law-abiding, hard-working Americans. The only surprising thing about the Tea Party backlash against Perry on immigration is that it took a few weeks to develop.

So why is a seasoned conservative ideologue like Newt Gingrich, who recently put forward a plan to offer a highly conditional “legalized” status to those certified as solid non-citizens by local panels, running the risk of saying anything on the subject other than “enforce the law”? It’s possible he’s trying to position himself to remain competitive with Hispanic voters in the general election, though that consideration hasn’t inhibited him from taking a variety of other positions that will cause problems if he happens to get the nomination. It’s more likely he thinks he’s found a sweet spot on immigration, whereby he can claim to oppose not only a “path to citizenship” but, just as importantly, deny public benefits to undocumented workers and their families (a key element of his plan) while avoiding the necessity of explaining how he’d deport 12 million people.