Tears, once kryptonite to serious presidential candidates, today are more often seen as a useful part of the political tool kit.

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Mitt Romney this week became the latest candidate to show his sensitive side. Tears welled in his eyes Monday as he spoke on the New Hampshire campaign trail about watching the casket of a soldier killed in Iraq.

"The soldiers that I was with stood at attention and saluted," Romney told employees at Insight Technology Inc., a company that makes infrared optical equipment for U.S. troops. "And I put my hand on my heart, and tears begin to well in your eyes, as you can imagine in a circumstance like that. I have five boys of my own. I imagined what it would be like to lose a son in a situation like that."

Eyes misting as he finished the story, Romney recalled glancing up at the massive windows in the U.S. Airways terminal.

"As I looked up there, every single hand was on every heart, and I recognized this is a nation that comes together and respects and reveres those who serve this great nation, and who joins in mourning when one of them is lost."

A day earlier, he choked up on NBC's "Meet the Press" in speaking about his religion.

The nation has come a long way in the 35 years since a New Hampshire sob story ended Sen. Edmund Muskie's 1972 presidential campaign. Muskie's campaign slid off the tracks after it was reported that he had cried in response to a newspaper attack on his wife. He went to his grave maintaining that it had been melted snowflakes, not a tear, in his eye.

Fifteen years later, in 1987, former Democratic Rep. Pat Schroeder got grief for crying as she announced that she would not be a presidential candidate.

She's still catching flak about it today, mostly from women.

"Oh, my gosh, I got a devastating e-mail about it from a woman writer just a couple of days ago," Schroeder said in an interview. "I want to say, 'Wait a minute, we are talking 20 years ago.' It's like I ruined their lives, 20 years ago, with three seconds of catching my breath."

Schroeder says she used to keep a "crying file" on weepy politician episodes, but it got so huge she threw it out.

"Guys have been tearing up all along and people think it's marvelous," Schroeder said, pointing to episodes stretching back to Ronald Reagan.

But for female candidates, crying clearly is still in the no-fly zone.

In her memoir, "Living History," Hillary Clinton wrote about the moment her husband admitted his affair with intern Monica Lewinsky.

"I could hardly breathe," she wrote. "Gulping for air, I started crying and yelling at him, 'What do you mean? What are you saying? Why did you lie to me?'"

But Clinton may shed no tears on the campaign trail. The same people who complain that she is cold and unemotional would seize on it as a sign of weakness and vulnerability, says Schroeder.

"For some reason," she says, "we still are a little nervous for women."

Aubrey Immelman, a political psychologist at the College of Saint Benedict and Saint John's University in Collegeville, Minn., said women "are in a default position" in the crying game.

"It would have bad consequences for Hillary if she teared up in public," Immelman said. "That's unfair, but I think that's probably how it still works in our society."

For male candidates, Immelman says, whether crying is OK or not "depends on context." Tough-guy candidates like Rudy Giuliani or John McCain, with his military background, can tear without fear, he says, and those talking about emotional issues such as fallen troops can emote without risk.

President George W. Bush, for example, often chokes up in talking about the war dead, or visiting with the victims of natural disasters.

Former President Clinton was such an eager emoter, says Immelman, that he "had a reputation for turning on and off the emotion to serve his own ends."

Romney, on the other hand, is seen as more stiff and formal. "For him to show a little bit of emotion could maybe soften that image a little bit," Immelman said.

"I'm a normal person, I have emotions," Romney told reporters. "I have emotion just like anyone else. I'm not ashamed of that at all."