WASHINGTON – In one of the stranger moments in Nevada Senate debate this past week, Sharron Angle, the ever-grinning, grandmotherly GOP Senate candidate, fired off the retort of the night.

“Man up, Harry Reid,” the 61-year-old said, dropping the smile, and blasting the Senate majority leader on Social Security.

Angle’s zinger stood out for its unexpected near-hipness. But in the current climate of political discourse, the fact that it was loaded with sexual stereotypes seemed hardly to register as controversial.

The 2010 election cycle may be remembered for a jarring shift in the political dialogue between the sexes, a moment when polite sensitivities were shelved and bold gender-based power plays became the norm.

The trend is clearest among a new class of conservative women — the “mama grizzlies” who pride themselves on a strong and irreverent post-feminist posture and frank rhetoric. Their leader, former Alaska Gov. Sarah Palin, set the tone when she told Fox News Channel in August that President Obama didn’t have the “cojones” to get tough on illegal immigration.

About a month later, Delaware Senate candidate Christine O’Donnell told a radio interviewer that her primary opponent should “put his man pants on.” Angle’s “man up,” coming from another so-called grizzly, seemed another link in that chain.

“The references to manliness have gotten more explicit,” said Deborah Tannen, an author and linguist who has studied communication between the sexes at Georgetown University. At the same time, Palin “has built a sort of brand on” such brash statements, while the culture at large is welcoming less formal conversation.

“The lines between public and private keep blurring, so ways of talking you used to do only in private you more and more do in public,” Tannen said.

To be sure, the trend isn’t exclusive to conservative women. Missouri Democrat Robin Carnahan also told GOP Rep. Roy Blunt to “man up” in their Senate debate this past week.

Male candidates also have used the phrase with increasing frequency — usually in an attempt to insinuate an opponent’s lack of political courage.

“At least man up and say I’m fat,” the rotund Republican Chris Christie said last year in answer to ads from former New Jersey Gov. Jon Corzine accusing him of “throwing his weight around.”

But experts in political discourse see another subtext, particularly when coming from a woman candidate.

“Male candidates have traditionally been assumed by would-be voters to be tough and competent. Women have traditionally been assumed to be caring and have to establish their competence,” said Kathleen Hall Jamieson, a professor of communication at the Annenberg Public Policy Center.

“‘Man up’ frames the attacker as tougher than the person attacked and suggests the male candidate is not taking responsibility or being accountable for his failures,” she said.

Others see the origins as more closely tied to the identity of the two political parties and the way they connect with voters.

George Lakoff, a professor of cognitive science and linguistics at the University of California Berkeley, describes the Republican Party as emphasizing masculinity and strength in its world view and rhetoric, while Democrats underscore the more feminine quality of empathy. Conservative women, in order to trigger cues in some voters, must project strength.

“If you’re a woman candidate who’s a conservative, then you have to say you’re more masculine than the other guy,” Lakoff said.

The boldly direct approach seems to suggest a double standard. It is hard to imagine a male candidate telling a female opponent to be more ladylike without facing repercussions. In fact, the candidates who have recently tripped up over comments deemed sexist were men.

In Colorado, Republican Senate candidate Ken Buck was widely criticized for telling voters to support him because, unlike his primary rival Jane Norton, “I do not wear high heels.” In California, Democratic candidate for governor Jerry Brown apologized to Republican Meg Whitman after an aide was recorded calling Whitman a “whore.”