WASHINGTON >> The shooting rampage in Arizona seems to have created a reset moment for confrontational politics, as lawmakers reflect on the repercussions of the overheated rhetoric traded on the airwaves and on the campaign trail.

Members of Congress from both parties called Sunday for civility over belligerence as the House temporarily shelved the contentious debate over repealing the health care law and lawmakers paused to contemplate the tragedy.

Critically wounded Rep. Gabrielle Giffords, the apparent target of a lone shooter, emerged as a potent and cautionary symbol of the current political climate. Still, there was no clear motivation for the attack, and some warned against making provocative politicians and commentators the culprits in the assault.

Six died and 14 were wounded in the shooting at a Tucson shopping center where Giffords was holding a gathering with constituents.

Authorities said the attack was the work of a single gunman. They described the apprehended suspect, 22-year-old Jared Loughner, as mentally unstable.

President Barack Obama will lead the nation in a moment of silence at 11 a.m. Monday. He has postponed a scheduled trip Tuesday to Schenectady, N.Y., where he planned to promote his economic policies. “It will be a time for us to come together as a nation in prayer or reflection, keeping the victims and their families closely at heart,” he said.

The Supreme Court said it plans to convene 10 minutes early on Monday, at 9:50 a.m., so the justices can observe the moment of silence at 11 a.m.

House Speaker John Boehner told lawmakers in a conference call Sunday to “pull together as an institution.”

“What is critical is that we stand together at this dark time as one body,” he said. “We need to rally around our wounded colleague, the families of the fallen, and the people of Arizona’s 8th District. And, frankly, we need to rally around each other.”

House Minority Leader Nancy Pelosi canceled a scheduled appearance Monday at the Detroit auto show.

Such unifying pauses are usual after national tragedies. The Sept. 11, 2001, terrorist attack was a coalescing moment in the nation that for a time improved the tone of Capitol Hill debate. Kathleen Hall Jamieson, director of the Annenberg Public Policy Center at the University of Pennsylvania and an expert on political rhetoric, said there were similar breaks after the assassinations of Robert Kennedy and Martin Luther King Jr.

“There was a lot of discussion about the meaning of the moment and what rhetoric had done to incite it,” she said.

What’s more, the attack on Giffords has given members of Congress a sense of unusual common purpose. Leaders from both parties worked together Sunday to offer members assurances that they were reviewing security measures.

Rep. John Larson, D-Conn., the chairman of the House Democratic Caucus, said his colleagues hope for “greater comity within the House and the discourse that takes place all across this country.”

Still, politics is a quarrelsome business and those breaks are short-lived. In the 1990s politicians lamented “the politics of personal destruction.” President George W. Bush was the subject of vicious criticism from the left, and President Obama has come under stinging, personal attack from some of his critics.

Congress has also become more partisan, with a dwindling number of moderate lawmakers. Veteran members of Congress have lamented a changed culture where legislators spend little time socializing with each other, a development that contributes to fewer cross-party relationships.

While Sunday’s calls for unity and civility were bipartisan, the discussion had a partisan subtext as Democrats pointed to anti-government language from the tea party movement and to rabble-rousing imagery and rhetoric from conservative figures such as Sarah Palin.

Sen. Dick Durbin, the second-ranking Democratic leader in the Senate, on Sunday mentioned Palin’s combative rallying cry, “Don’t retreat; reload,” and the crosshairs she used to signal congressional districts where she wanted Republicans to win.

“These sorts of things, I think, invite the kind of toxic rhetoric that can lead unstable people to believe this is an acceptable response,” Durbin said Sunday on CNN.

Republicans were especially sensitive to suggestions that their side of the political spectrum was contributing to a more poisonous political environment.

Sen. Lamar Alexander, R-Tenn., noted Sunday that the suspect in the Tucson rampage was connected to Internet postings that included Marxist and Nazi literature.

“That’s not the profile of a typical tea party member, if that’s the inference that’s being made,” he said on CNN.

To be sure, combative language in politics is not the province of a single party. It was Obama who declared during the 2008 presidential campaign, “If they bring a knife to the fight, we bring a gun.” And Sen. Joe Manchin, a West Virginia Democrat, ran ads during last year’s campaign that portrayed him with a high-powered rifle, placing a cap-and-trade energy bill in the crosshairs and blasting it to pieces.

The Tucson shooting could also result in hypersensitivity, where lawmakers take any partisan comment as an invitation to incite a fight.

“The danger in this is that people misread it and so the first time that someone makes a statement that is partisan, it’s condemned as inappropriate,” Jamieson said.

Experts say angry political language is made all the more prevalent by the Internet and opinion-driven cable television, amplifying the sense of confrontation. Jamieson says she doesn’t believe current Congresses have been more uncivil than past one.

“But the media culture has given us access to incivility that probably was there all along but didn’t have that much accessibility,” Jamieson said. “The consequence of broader exposure is that it becomes normalized.”

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Associated Press writer Douglass K. Daniel contributed to this report.