One of the strangest things about the immigration debate is the fervent belief by conservatives that President Obama is motivated only by devious partisan considerations. Immigration hawk David Frum notes, “the president’s political opponents almost unanimously believe that his act of nullification is motivated by the crassest kind of political calculation.” (Frum does not endorse this belief among conservatives, he merely passes it on.) Michael Gerson — like Frum, a former Bush speechwriter, and unlike Frum, a strong proponent of immigration reform — argues that Obama “uses undocumented workers in a vast political ploy.”

This is a strange belief, first of all, because it fails to recognize the blindingly obvious humanitarian motive that surely supplied much of Obama’s incentive. Obama is a liberal Democrat. Liberal Democrats like immigrants. They want to do something to help the millions of people who have committed a victimless crime in order to give their children a better life.

The second and even stranger thing about conservative suspicions is that they seem not to have fed back into the right’s own decision-making matrix. Obama has been threatening to, for months on end, act unilaterally if Republicans would not pass a bill. The threat such an action posed should have been obvious enough to spur Republicans to head it off. Passing some kind of bill through the House, even one that fell far short of Obama’s ambitions, would have placed the president in a tough spot, muddying the political issue and making his unilateralism harder to sustain. Rather than complain about Obama’s diabolical maneuver, they should have thought about maybe preventing it.

It is clear that Obama’s executive action places Republicans in a near-impossible spot. The newest evidence is a poll this week from Latino Decisions, finding that 89 percent of Hispanics support Obama’s move. Now, the wording of the poll, which repeats Obama’s justification but not Republican objections, likely inflates support. Still, it seems to suggest extremely high levels of support. If, as seems likely, the next Republican nominee is forced to promise to overturn it during the primary, it will lock the GOP into a stance of implacable hostility toward the overwhelming majority of the Latino community.

Why have Republicans allowed themselves to be felled by such a telegraphed punch? Internal dysfunction plays a major role, of course, along with sheer distrust. But one underappreciated factor may be that Republicans have come to rely on a strategy that works extremely well in other cases.

The GOP has withheld cooperation from every major element of President Obama’s agenda, beginning with the stimulus, through health-care reform, financial regulation, the environment, long-term debt reduction, and so on. That stance has worked extremely well as a political strategy. Most people pay little attention to politics and tend to hold the president responsible for outcomes. If Republicans turn every issue into an intractable partisan scrum, people get frustrated with the status quo and take out their frustration on the president’s party. It’s a formula, but it works.

The formula only fails to work if the president happens to have an easy and legal way to act on the issue in question without Congress. Obama can’t do that on infrastructure, or the grand bargain, and he couldn’t do it on health care. But he could do it on immigration. So Republicans were stuck carrying out a strategy whose endgame would normally be “bill fails, public blames Obama” that instead wound up “Obama acts unilaterally, claims credit, forces Republicans to take poisonous stance in opposition.” They had grown so accustomed to holding all the legislative leverage, they couldn’t adapt to a circumstance where they had none.