Republican presidential candidate Donald Trump slammed Democratic front-runner Hillary Clinton, saying that "the only card she has is the woman's card." (Reuters)

Republican presidential candidate Donald Trump slammed Democratic front-runner Hillary Clinton, saying that "the only card she has is the woman's card." (Reuters)

“I wasn’t playing the woman’s card,” Donald Trump said Thursday when asked about his claim that Hillary Clinton was playing the “woman card” and that if she were a man, she would get only 5 percent of the vote.

For once, I agree with Trump: He wasn’t playing the woman card. He was playing the man card — and he was dealing from the bottom of the deck.

Trump’s return to misogyny — unveiled on Tuesday night, at the very moment when he seemed to have secured the Republican presidential nomination — has been generally viewed as bumbling, a reprise of the days when he used “slob,” “dog” and “piece of ass” to describe women.

But Trump’s gender-based attack on Clinton, which he defended in subsequent days, was likely no accident. Research shows the attack is rational, and his repetition of it suggests it’s calculated.

Trump orchestrated his primary campaign success on the basis of economic and racial resentment. Now he’s building a general-election strategy — against the first woman to lead a major party’s presidential ticket — on gender resentment.

Alexandra Petri explains the perks that come from signing up for a "woman card." (Adriana Usero/The Washington Post)

It probably won’t work. It definitely is ugly. But it may be the best card he has to play, with 7 in 10 women regarding him unfavorably. A man who has demagogically divided Americans by race and ethnicity now aims to finish the job by dividing us by views of gender roles.

A fascinating new study by Dan Cassino, a political scientist at Fairleigh Dickinson University in New Jersey, shows why. Just as Trump has exposed a surprising depth of racial animus in the United States, there is gender animus to be tapped as well. Cassino found that the “gender role threat” — a perceived threat to male identity and masculinity — leads to increased support for Trump among men, and lower support for Clinton.

In a survey of New Jersey voters in late February, Cassino and his colleagues tried an experiment. Half of respondents, before being asked about their preference in the presidential election, were asked whether they or their spouse earned more money. The others were asked about their household income distribution after they were asked about their presidential preference.

What they found was troubling — and huge. Men who weren’t “primed” with the question about spousal income preferred Clinton over Trump, 49 percent to 33 percent. But those who were primed with the income question, reminding them about the upending of traditional gender roles, favored Trump over Clinton, 50 to 42 percent — a 24-point shift. Removing any doubt that the issue is gender: The same experiment produced almost no shift in a hypothetical matchup between Trump and Sen. Bernie Sanders (I-Vt.).

The priming of voters with the gender-role question caused women to support Clinton even more strongly, by an extra 12 percentage points. But this didn’t offset the losses the experiment caused Clinton among men. Overall, she lost 8 percentage points when voters were reminded about changing gender roles.

What this shows, and what Trump apparently recognizes, is that the gender gap cuts both ways. Trump has already lost the votes of liberal and moderate women (and of liberal men, who, like women, tended to be even more pro-Clinton when they were primed with the gender-role question). Playing the man card — appealing to a male sense of feeling threatened by changing gender roles — can help Trump boost turnout among conservative and evangelical Christian men, while peeling off some support from non-white men and older, anti-feminist women.

The gender gap “probably hurts him more than it helps him, but it’s close,” Cassino told me. “I don’t think it’s a big loser in the general election.”

Cassino (who made waves a few years ago with a study showing that news outlets such as Fox News and MSNBC had a negative effect on viewers’ knowledge of current events) sees the man card as an extension of the implicit theme that has worked for Trump so far. “It says white men used to run everything and now we don’t and it’s terrible,” he said. “We were focusing on the ‘white’ part before, and now we’re focusing on the ‘men’ part. It’s all the same appeal.” After the presidency of an African American exposed more latent racism in “post-racial” America than many thought existed, the presidential nomination of a woman will bring out latent sexism.

So the next time you hear Trump talking about how Clinton would get only 5 percent of the vote if she were a man, or about the blood coming out of Megyn Kelly’s “wherever,” or how both Clinton and Carly Fiorina give him headaches, or about the pain caused him by Clinton’s “shouting” even though “you can’t say that about a woman,” consider this: Trump isn’t boorish and bumbling. He is coldly calculating.

Twitter: @Milbank

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