SCOTTSDALE, Ariz., April 14 — Al and Diane Kitlica have not paid close attention to the immigration debate in Congress. But when more than 100,000 mostly Hispanic demonstrators marched through Phoenix this week, the Kitlicas noticed.

 

"I was outraged," Ms. Kitlica told J. D. Hayworth, the Republican who is her congressman, as she and her husband stopped him for 20 minutes while he was on a walk through their suburban neighborhood to complain to him about the issue.

 

"You want to stay here and get an education, get benefits, and you still want to say 'Viva Mexico'? It was a slap in the face," Ms. Kitlica said, adding that illegal immigrants were straining the Mesa public school where she teaches.

 

A few miles west, Gus Martinez, a Mexican immigrant who was moonlighting at a hot dog stand after a day installing drywall, said the protests had changed his perspective, too.

 

Mr. Martinez, who said he was a legal immigrant, said he also supported border security to curb illegal entry. But he had taken the day off to march earlier in the week because he believed that the foes of illegal immigration were taking aim at Hispanics as a group. The demonstrations, he said, had instilled in him a sense of power.

 

"It showed that our hands — Latino hands — make a difference in this country," Mr. Martinez said. "They see you are Hispanic and call you a criminal, but we are not."

 

As lawmakers set aside the debate on immigration legislation for their spring recess, the protests by millions around the nation have escalated the policy debate into a much broader battle over the status of the country's 11 million illegal immigrants. While the marches have galvanized Hispanic voters, they have also energized those who support a crackdown on illegal immigration.

 

"The size and magnitude of the demonstrations had some kind of backfire effect," said John McLaughlin, a Republican pollster who said he was working for 26 House members and seven senators seeking re-election. "The Republicans that are tough on immigration are doing well right now."

 

Mr. Hayworth said, "I see an incredible backlash." He has become one of the House's most vocal opponents of illegal immigration and is one of dozens of Republicans who have vowed to block the temporary-worker measure that stalled in the Senate.

 

The Kitlicas, who had been unaware of his views, decided to volunteer for his campaign. Mr. Hayworth, who has been singled out by Democrats in his bid for re-election, faces a challenge from a popular former Democratic mayor of Tempe, Harry E. Mitchell.

 

The immigration issue is cropping up in areas as far from the border as Iowa and Nebraska. In one House district in Iowa, Republican primary candidates are running television commercials competing over who is "toughest" on illegal immigration, said Amy Walters, an analyst with the nonpartisan Cook Political Report.

 

Representative Steve King, an Iowa Republican from another district, said his office had been flooded with angry calls about the recent marches. "It is one thing to see an abstract number of 12 million illegal immigrants," Mr. King said. "It is another thing to see more than a million marching through the streets demanding benefits as if it were a birthright." He added, "I think people resent that."

 

But Mr. King, who supported a House bill to restrict illegal immigrants without creating a guest-worker program, said he was also feeling new heat from the thousands of Hispanics in his district, many of whom worked in its meatpacking plants. Responding to a survey by his office, some Hispanics called him a racist for asking questions about building a wall with Mexico, or suggested a wall with Canada, he said.

 

The emotions around the issue are especially intense in Arizona, where thousands of illegal immigrants cross the border each month and more than a quarter of the population is Hispanic. In 2004, Hispanics accounted for about one in eight voters.

When voters approved a ballot measure that year to block access to state services for illegal immigrants, more than 40 percent of Hispanic voters supported it, according to some surveys of people leaving polling places.

 

But many Hispanics said opinions had changed dramatically in the past few weeks, partly because of the hostility they perceived in some proposals from Mr. Hayworth and other conservatives.

 

"When people are talking about shooting people who come across the border," said Harry Garewal, chief executive of the Arizona Hispanic Chamber of

Commerce, "yeah, I think that causes some angst."

 

Leo Hernandez, assistant publisher of Prensa Hispana, a major Arizona Spanish-language newspaper, said the demonstrations had also played a role. "The Latino people in Arizona are more united," Mr. Hernandez said. "They are no more afraid; they go out into the streets."

 

In Scottsdale, where many employees are Hispanic but few residents are, some voters said the workplace absences on the day of the marches highlighted the importance of immigrant labor.

 

"If you don't get the Hispanics here working in this town, you don't have cooks in the back, you don't have people building houses," said Bruce Weinstein, an executive eating breakfast at a restaurant.

 

Many others, however, expressed alarm about the marches, saying the demonstrations could have been a chance to round up and deport illegal immigrants.

 

"They should all be ejected out of the country," said Andrew Chenot, a construction worker, who added, "They are in my country and they are on my job, and they are driving down wages."

 

Others here, like the Kitlicas, said the marches had only sharpened their worries that illegal immigrants from Mexico brought with them crime, financial burdens, national security risks, cultural disintegration and even diseases like drug-resistant tuberculosis — concerns echoed often by conservative talk radio hosts in the state.

 

Representative Hayworth said such fears were well-founded. "We have indicted felons from other societies on the loose here," he said. "You see the exponential rise of drug-resistant T.B. and other things. That is not indicting an entire culture, but it is pointing out a problem."

 

Mr. Hayworth recently published a book, "Whatever It Takes" (Regnery Publishing, 2006), in which he advocates enlisting agencies like the Internal Revenue Service to find illegal immigrants; arresting and deporting them all; deploying military troops on the southern border; and temporarily suspending legal immigration from Mexico.

His opponent, Mr. Mitchell, calls those ideas "unrealistic."

 

Randy Graf, a former Republican state legislator, is campaigning on the same border-security themes as Mr. Hayworth in his bid to succeed Representative Jim Kolbe, a Republican and a supporter of a temporary-worker program who is not running again.

 

Mr. Graf challenged Mr. Kolbe in the primary two years ago over the immigration issue and won 40 percent of the vote, putting him in a strong position against two more moderate Republicans in the primary.

 

Mike Hellon, one of the more moderate candidates in the current primary, said: "The marches have hardened positions on both sides. People who really want the border closed — who want to put troops down there — are more passionate than ever, and the other side is more sympathetic." He added, "It does escalate the risk factor for a moderate like me."

 

Representative Raúl M. Grijalva, an Arizona Democrat who supports a temporary-worker program that would allow illegal immigrants a path to citizenship, said that House conservatives like Mr. Hayworth remained a major obstacle to such legislation. "That is the oil in the water," Mr. Grijalva said.

 

But with the Hispanic electorate set to swell as the children of immigrants come of age, Mr. Grijalva said that history was on the other side.

 

"You might be getting a momentary bump," he said, "but in the long run you are going to lose."