WASHINGTON — If Joe Barton's career ends because of a lewd video he sent to a lover five years ago, he'd be the rare congressman felled by a consensual, if icky, sex tape.

Others have seen their ambitions derailed by visits with prostitutes, payoffs to mistresses, come-ons to underage pages, groping in elevators, demands on aides for sexual favors, and extramarital dalliances. Barton's embarrassment may be no easier to live down. In the internet age, the images and snickers spread fast.

But based on what's known so far, the Ennis Republican engaged only in private, victimless behavior, in an era when sexting isn't so unheard of, even by 60-something politicians.

He's no Gary Hart or David Vitter or Bob Packwood, let alone a Roy Moore or Al Franken. That gives him a chance to survive, if he can show that "he is not part of that narrative of a powerful man behaving badly — that it wasn't an abuse of power," said political scientist Hinda Mandell, an expert on sex scandals.

Barton, the senior Texan in Congress and former chairman of the powerful energy and commerce committee, apologized Wednesday after exposure of a video he'd sent to a woman with whom he had struck up a relationship. The video shows him masturbating. A screen shot, with his genitals blurred out, bounced around social media for days before he was forced to acknowledge it was him.

"The risk just seems so much higher than the sexual rewards," said Mandell, a professor at the Rochester Institute of Technology whose books include Sex Scandals, Gender, and Power in Contemporary American Politics. "What was he thinking? That is a rational question. But what these men are doing is not rational. It's driven by desire, by embracing risk, by compulsivity."

Can he survive? That depends. Barton has never been much of a public moralizer, which shields him from allegations of hypocrisy. He could have enough good will banked for constituents to forgive his foibles, and draw a bright line between seamy but private behavior and the sort of harassment and abuse of power allegations leveled at other politicians.

The calculus would change if more revelations emerge, especially given the current climate.

"She's not a pole dancer. She's not a lady of the night," said Ross Baker, a congressional scholar at Rutgers University. "This is not Roy Moore. ... It may not be praiseworthy, but there should be some zone of privacy even for relationships that in the strictest sense may be regarded as illicit or unconventional. Even public figures deserve that privacy."

Private lives of public figures

Decades ago, exposure of love letters to a mistress could throw a presidential campaign into turmoil. On the other hand, as recently as John F. Kennedy, journalistic norms dictated ignoring peccadilloes. American political history is replete with such scandals.

Norms began to shift in 1974, when U.S. Park Police pulled over a car speeding at the Tidal Basin. The driver was Arkansas Democrat Wilbur Mills, chairman of the powerful House Ways and Means Committee, and his companion was an Argentine stripper known by her stage name, Fanne Foxe. Both had been drinking. An alert TV cameraman captured the scene. The married congressman lost his chairmanship and was shamed out of seeking re-election.

Then came Gary Hart.

In 1987, the Colorado senator led the Democratic field for president, despite rumors of infidelity spread by rivals. He dared the media to "follow me around." A team from the Miami Herald established that he'd spent a weekend with Donna Rice, a woman he'd also gone to the Bahamas with aboard a yacht named "Monkey Business."

The zone of privacy for politicians would never be the same, though politicians often enough invited attention through their missteps.

In 2007, Sen. David Vitter, a Louisiana Republican, confessed to "a very serious sin" after his name turned up on the "D.C. Madam" list of escort service clients. Voters re-elected him in 2010, but the prostitution scandal caught up with him in a failed governor's race in 2015.

Rep. Mark Foley, a Florida Republican, resigned in 2006 after revelations of sexually suggestive texts and emails to underage male congressional pages.

The list goes on and on.

In the current climate, situations involving sexual aggression and unwanted touching are the most politically damaging.

Based on Mandell's research on prior scandals, Barton has some factors in his favor and others against him.

The longer the career, the better the odds of survival; Barton has served 35 years in the House, more than half his life. He'll need colleagues in Congress to stick by him publicly; he'll know soon enough, when Thanksgiving break ends.

And he'll need to persuade voters that his story is credible: That he never intended disclosure of intimate material, and he is getting caught up in a larger social dynamic as one powerful figure after another faces sexual misconduct allegations.

That likely entails an on-camera public reckoning, because "America really values a sincere apology. It's the Oprah Winfrey syndrome."

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Trivial by comparison

The Oxford English Dictionary added "sexting" in 2011, a few months after New York Rep. Anthony Weiner accidentally posted an explicit photo of himself on his public Twitter account. He resigned within weeks.

Barton's transgression seems trivial compared to the allegations against Charlie Rose or Harvey Weinstein, who abused their clout in newsrooms and Hollywood to pressure subordinates for sex.

Nor do Barton's lewd messages compare to the allegations facing Roy Moore, the U.S. Senate nominee in Alabama accused of illegal sexual contact with a 14-year-old when he was a prosecutor in his 30s, and of sexual assault on a 16-year-old.

The Texan's situation also differs from misdeeds by Sen. Al Franken, the Minnesota Democrat who recently apologized for a photo that shows him groping — or simulating it — a fellow performer during a USO tour in 2006.

But congressional careers have ended over less explicit sexting than Barton's.

In February 2011, Rep. Christopher Lee, a Republican from upstate New York, abruptly resigned after the website Gawker revealed that he'd sent a bare-chested photo of himself and other "flirtatious e-mails" to a woman he'd contacted through Craigslist.

The photos weren't nudes. There was no masturbation. But Lee was married and the father of a young boy, and had lied by telling the woman he was a divorced lobbyist. He also used his congressional email account.

(Gawker went bankrupt in 2016 and was shuttered after it published video showing former pro wrestler Hulk Hogan having sex with a friend's wife. Hogan sued for invasion of privacy.)

Other Texans

Barton isn't the first Texan in Congress caught up in a sex scandal.

In 1976, a former secretary accused Rep. John Young, a Corpus Christi Democrat, of demanding sexual favors in exchange for a pay raise. He denied it, insisting that those repeated visits to motels were actually secret meetings with military officials.

Young's wife killed herself in 1977. The next year, voters ousted him, ending a 22-year House career.

Young sued The New York Times for libel, along with his accuser's lawyer. The $6 million lawsuit was thrown out, and he died in 2002 after a post-congressional career as a lobbyist.

As for the rival who beat Young in the 1978 primary, Joseph Wyatt of Victoria — he would serve just one term. The former state lawmaker and aide to Lyndon Johnson was arrested shortly after taking office on charges of forcible sex with another man. He didn't seek re-election.

Then there was John Tower, who represented Texas in the Senate for 24 years. In 1989, he became the first Cabinet nominee rejected in three decades, his bid to become secretary of defense derailed by allegations of heavy drinking and womanizing, and questions about his ties with defense contractors.

Deadline looming

Barton's opponents have two weeks to decide whether to jump into the March primary, and likewise, he has two weeks to decide whether to stick by the decision announced three weeks ago to seek an 18th term.

At last check, he had $400,000 in his campaign account — plenty to scare off challengers in ordinary times but not nearly enough for a protracted fight if an opponent decides to use the sexting scandal to smear him.

"I don't think he's that politically vulnerable," said Allan Saxe, a political scientist at the University of Texas at Arlington who has tracked Barton's career for years. "I think most people will slough it off. They may laugh or giggle but then go about their business."

He compared Barton — favorably — to Oregon Sen. Bob Packwood, a Republican who resigned in disgrace in 1995 after dozens of women accused him of unwanted sexual advances. For years, Packwood was known to accost aides, journalists and lobbyists in elevators at the Capitol, and the Senate Ethics Committee recommended expulsion.

"We lump all these together. They need to be separated out. ... Joe Barton didn't grab anybody. Nothing was nonconsensual in this as far as we know," Saxe said. "We love to see the powerful fall, but it's a private matter that unfortunately went public. It's embarrassing, but that's all.

"It must be a nightmare for him," he said.