Exchanges on the House floor were growing heated and vicious. Cooperation between parties had ground to a halt – and had already led to a shutdown of government. Worried about the future of Congress itself, 86 members sent a letter to the speaker requesting an urgent, bipartisan retreat to focus on one thing: building civility.

Laura Chasin, founder of the Public Conver­sa­tions Project, helped facilitate discussions at that 1997 congressional retreat in Hershey, Pa., and describes a “very moving” scene. Members were asked how the acrimony in public life affected them. “And the stories that came out,” she says, “oh, my.” One congressman from the Southwest, “with tears streaming down his face,” Ms. Chasin recalls, said he’d gotten into politics to help people, but found himself in town-hall meetings “just gritting his teeth. The abuse had become so horrible.”

Now, 15 years later, it seems the tone in Wash­ington – and around the country – is, if possible, even more divisive and ugly. Last summer, with a stagnant economy and emotions over the health-care reform bill raging, some members wound up canceling town-hall meetings altogether because they were deteriorating into shouting matches.

And while hostile rhetoric may not have been a factor in the alleged assassination attempt in Tucson of Rep. Gabrielle Giffords (D) of Arizona, it was an issue that she herself had made a priority. Her widely reported e-mail sent to Kentucky’s Republican secretary of state, Trey Grayson, the day before she was wounded in a mass shooting is a clear indictment of the problem. Congratulating him on being named president of Harvard’s Institute of Politics, she added: “After you get settled, I would love to talk about what we can do to promote centrism and moderation. I am one of only 12 Dems left in a GOP district (the only woman) and think that we need to figure out how to tone our rhetoric and partisanship down.”

In the immediate aftermath of Ms. Giffords’s shooting, these divisions have again been on display, as some partisans on the right and left have pointed fingers and accused one another of unfairly assigning blame.

“That is precisely what is wrong with our dialogue,” Stephen Car­ter, a law professor at Yale University and author of “The Vio­lence of Peace,” observed in an e-mail interview. “Everything that happens, from the trivial to the tragic, is viewed across the spectrum as simply another opportunity to bash the opposition.”

Yet many have also responded to the shooting with calls for unity. Indeed, in his Jan. 12 speech at the memorial for the victims of the Tucson shooting, President Obama urged Americans to talk “with each other in a way that heals,” declaring that “what we cannot do is use this tragedy as one more occasion to turn on each other.”

And to a growing number of activists and experts in the business of civility, it appears partisan rancor is reaching a tipping point. They say that changing the tone of political rhetoric can’t be just a vague aspiration, but is an absolute imperative – and must take the form of a concrete, organized effort.

More to the point, many believe it’s doable.

“This is possible,” insists Nancy Jacobson, a longtime Democratic fundraiser and cofounder of the new bipartisan group No Labels, which defines its mission in part as supporting politicians who put labels aside and work across the aisle.

No Labels aims to represent what it sees as the underserved “majority” of Americans, whose views lie in the center of the political spectrum, rather than at the extremes. Instead of policy and issues, the focus is on “attitude and approach”: finding ways to support and reward – rather than punish – politicians who reach across the aisle. The group’s “code of conduct” for politicians is centered on civility and respect. “What we are about is changing behavior,” says Ms. Jacobson. “And putting pressure on politicians to do just that.”

No Labels has already drawn criticism and even derision from some (New York Times columnist Frank Rich mocked the group’s “faith in kumbaya as an antidote to what ails a polarized Washington”). But there’s evidence that its efforts have an audience. A 2010 survey by the Center for Political Participation at Allegheny College in Meadville, Pa., found a “growing concern about the implications of an uncivil body politic.” Citizens paying “close attention” to politics were four times more likely to say the tone in politics had gotten worse in recent years. And 95 percent said civility in politics was important for a healthy democracy.

“To me, it’s so clear that it’s in the interests of the American people to have the parties actually dialoguing,” says Mark Gerzon, founder of the Mediators Foundation. Mr. Gerzon, who facilitated bipartisan congressional retreats from 1995 to 2007, points to a growing network of groups fostering Democratic-Republican dialogue at federal, state, and community levels. Efforts like this can have a profound effect, he says: By the end of a 1997 House retreat, “people said, ‘I don’t remember who’s a Democrat and who’s a Republican.’ ”

Key to the retreat’s success, says Gerzon, were the ground rules: “No personal attacks”; “When others speak, listen”; “Be open to other points of view”; and “Treat the sessions as confidential.” It did change the way members did business, if temporarily. A study by the Annenberg Public Policy Center at the University of Pennsylvania in Philadelphia found noticeable improvement in civility on the floor of the House immediately after the retreat. Members were more likely to express desire for compromise as name-calling, aspersion, and hyperbole dropped.

An obstacle to a more civil tone, says Gerzon, is Congress’s setup, particularly in the House, where power lies with party leaders, who dictate strategy and punish those who fall out of line. “If [members] don’t want to play the A versus B game ... then they’re a traitor to the party. It’s a very uncreative way of creating legislation.”

And extreme rhetoric is an effective – often irresistible – way to grab the spotlight. “One way to get attention is to be more vitriolic,” says Deborah Tannen, author of “The Argument Culture.” Politicians looking for visibility, and media worried about losing viewers, readers, or listeners, have incentives to amp up the volume.

Ultimately, experts agree, when it comes to lasting change, both sides need a motivating force. “There has to be an answer to the ‘why’ – ‘why change?’” says Chasin. She gives the example of a series of successful dialogues she facilitated between a group of pro-choice and pro-life activists after the 1994 fatal shootings at two abortion clinics in the Boston area. Both sides, she says, were seriously afraid of further violence. “They had an answer to the ‘why’ – and they did it.”

And while it may be hard to quantify what those discussions achieved in practical terms – “successful prevention is very hard to prove,” Chasin admits – the two sides found new levels of respect for one another. They shared information, and at one point went to the FBI together. The original plan for four meetings turned into a five-year dialogue.

It’s too early to tell if the Giffords shooting acts as a similar catalyst, but in the short term, higher levels of restraint are apparent. A planned showdown over repealing parts of Mr. Obama’s health-care bill was postponed, and some are calling for new ways to come together.

“I think an event of this kind has a profound impact on politicians,” says former Indiana Congressman Lee Hamilton, now the director of the Center on Congress at Indiana University. “At least for a period ... they will exercise second thoughts about very strong, vitriolic rhetoric.”

Mr. Hamilton hopes the shootings won’t discourage members from meeting the public: “It’s terribly important to a representative to have that close touch.... A threat to that give-and-take is a threat to the very core of the democratic process.”

The process may be contentious, but it’s no excuse for toxic rhetoric, adds Hamilton, who – as a leader of the Iraq Study Group and of the 9/11 commission, forged consensus on tough issues. “I think we have to get back to a much more civil discussion in the country – and to recognize that this is a great big complicated country,” he says. “We shouldn’t fall out of our chairs because someone disagrees with us, but the manner in which you disagree makes an awful lot of difference in society.”