(AP/Matt York)

Poll after poll shows Hillary Clinton is not popular among white men. Her policy stances haven’t won their admiration. A cultural shift toward feminism hasn’t helped much, either.

But the Democratic front-runner in the presidential campaign has a secret weapon, one that could help her snare crucial voters from presumptive Republican nominee Donald Trump: her husband.

The idea may seem counterintuitive, especially since Trump intends to use Bill Clinton’s philandering past against his wife.

New research from Lauren Wright, a political consultant and author who just finished her PhD in government at Georgetown University, suggests the potential first gentleman could sway a surprising demographic. She recently surveyed more than 4,200 people nationwide, ages 19 to 85, about how they perceive Hillary Clinton.

Wright attached to the questionnaires one of two photos — one of Clinton by

Photo 1 of Hillary Clinton. (Courtesy of Lauren Wright)

herself and one with Clinton and the former president. Then she asked respondents if Hillary Clinton looked compassionate and honest.

A trend emerged: Republican men who viewed a picture of the couple, rather than the candidate alone, rated Hillary Clinton as much more likable. Her husband’s presence, it turned out, increased her popularity.

Asked if she seemed “down to earth,” the Republican men who saw the smiling pair responded 14 percentage points more favorably than those who just saw Hillary Clinton alone. Bill Clinton's presence also drove a 12 percentage point increase among Republican men when asked whether Hillary Clinton is truthful or “cares about people like me," compared to when she appeared alone.

Respondents could answer each question — how well does “down to earth” or “honest” or “cares about me” describe Clinton — on a four-point scale, with one being “not too well at all” and four being “extremely well.” They were also asked to rate her as a candidate on a scale from 0 to 100.

Photo 2 of Hillary and Bill Clinton. (Courtesy of Lauren Wright)

Wright rescaled the variables to display them on the same graph and interpret them in terms of percentage point change. (Sample 1 refers to answers collected last June, and sample 2 was surveyed in March.)

Photo courtesy of Lauren Wright

(Bill Clinton's presence in the photo had the opposite effect on Democratic men and women; they viewed Hillary Clinton on her own in a more positive light. Republican women's responses didn't statistically differ.)

A late April CNN/ORC poll found that 52 percent of men had an unfavorable view of Hillary Clinton, compared with 45 percent who had a favorable view. The March Post-ABC poll revealed similar attitudes: 61 percent had a negative opinion on the candidate, while 38 percent had positive feelings about her.

But Wright wasn’t surprised that pairing Hillary Clinton with her husband apparently improved her image among Republicans. Her previous research, published in her new book "On Behalf of the President," focused on the little-explored power of America’s first ladies over voters across party lines.

The former president, of course, could become the first man to occupy the role of presidential spouse. Hillary Clinton told voters in Kentucky this weekend that what her husband would do as first gentleman is already mapped out: He would focus on “revitalizing the economy, because, you know, he knows how to do it.”

Wright spent months digging through old speeches, interviewing former White House staffers and measuring the impact of each Michelle Obama or Laura Bush appearance in the press and on social media. She concluded that presidential spouses wield more influence on people who probably voted against their husbands than other surrogates, including the vice president.

Wright has also conducted experiments in which she gave people excerpts of the same speech and then told them that either the president or the first lady wrote it. People tended to respond slightly better to the policy points, she said, if they believed the first lady delivered them.

Their messages land with less apparent agenda, she said. They’re also boasting about a loved one, not themselves. And they don’t come off as politicians, which is why they may appeal more to people across party lines.

How could Bill Clinton, the ultimate politician, create the same effect?

“American voters have a very short attention span,” Wright said of Clinton's former leadership. “So, he’s an image softener. He vouches for her character — the same things spouses do very well.”

He’s also careful not to place himself front and center, Wright said. Bill lightly adds to Hillary’s platforms and, with a little self-deprecating humor, makes her seem more human. (“She's always trying to improve me,” he said on a morning show, “so I'm having to get used to being improved more regularly.”)

It’s tough to explain why Wright’s  sample of Republican men favored the former first couple over Hillary Clinton alone. Maybe they don’t like seeing a woman run for president. Maybe family is the universally beloved visual. Maybe they just like Bill.

Susan Carroll, professor of political science and women's and gender studies at Rutgers University, offered a more Tammy Wynette theory: Hillary Clinton scored points from Republican men because she stood by her man.

“When you place her with him, it reminds them that she stood by Bill Clinton through his infidelities,” Carroll said. “She stuck it out. She forgave him. That's what most men would want the women in their lives to do.”

The memory could make her more sympathetic, especially among social conservatives who find divorce unappealing.

“It's hard to look at a picture of the two of them,” Carroll said, “and have the Monica Lewinsky episode not come to mind.”

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