WASHINGTON — The shooting of Representative Gabrielle Giffords and others at a neighborhood meeting in Arizona on Saturday set off what is likely to be a wrenching debate over anger and violence in American politics.

While the exact motivations of the suspect in the shootings remained unclear, an Internet site tied to the man, Jared Lee Loughner, contained antigovernment ramblings. And regardless of what led to the episode, it quickly focused attention on the degree to which inflammatory language, threats and implicit instigations to violence have become a steady undercurrent in the nation’s political culture.

Clarence W. Dupnik, the Pima County sheriff, seemed to capture the mood of the day at an evening news conference when he said it was time for the country to “do a little soul-searching.”

“It’s not unusual for all public officials to get threats constantly, myself included,” Sheriff Dupnik said. “That’s the sad thing about what’s going on in America: pretty soon we’re not going to be able to find reasonable, decent people willing to subject themselves to serve in public office.”

In the hours immediately after the shooting of Ms. Giffords, a Democrat, and others in a supermarket parking lot in Tucson, members of both parties found rare unity in their sorrow. Top Republicans including Speaker John A. Boehner and Gov. Jan Brewer of Arizona quickly condemned the violence.

“An attack on one who serves is an attack on all who serve,” Mr. Boehner said in a statement. “Acts and threats of violence against public officials have no place in our society.”

President Obama made a brief appearance at the White House, calling the shooting an “unspeakable act” and promising to “get to the bottom of this.”

Not since the Oklahoma City bombing in 1995 has an event generated as much attention as to whether extremism, antigovernment sentiment and even simple political passion at both ends of the ideological spectrum have created a climate promoting violence. The fallout seemed to hold the potential to upend the effort by Republicans to keep their agenda front and center in the new Congress and to alter the political narrative in other ways.

The House was set to vote Wednesday on the new Republican majority’s proposal to repeal the health care law that had energized their supporters and ignited opposition from the Tea Party movement. Representative Eric Cantor of Virginia, the new majority leader, said Saturday that the vote and other planned legislative activity would be postponed.

The original health care legislation stirred strong feelings that flared at angry town hall meetings held by many Democratic lawmakers during the summer of 2009. And there has been broader anger and suspicion rising about the government, its finances and its goals, with the discourse partially fueled by talk shows and Web sites.

Tea Party activists also condemned the shooting. Judson Phillips, the founder of Tea Party Nation, noted on his Web site that Ms. Giffords is “a liberal,” but added, “that does not matter now. No one should be a victim of violence because of their political beliefs.”

But others said it was hard to separate what had happened from the heated nature of the debate that has swirled around Mr. Obama and Democratic policies of the past two years.