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Sen. John McCain pressed the flesh at a Memorial Day event in Prescott, Ariz., Sunday before opening up a new campaign office in that town while the man who wants to take his seat was in Washington, D.C., to debate immigration policy.

The reverse in venue offered a glimpse into the frenetic Republican primary contest in the Grand Canyon State, which has been consumed by a new state immigration law that has rippled through the rest of the nation.

The influx of millions of illegals through the porous Mexico-Arizona border is the top issue for McCain and former Rep. J.D. Hayworth as the two vigorously battle in the toughest Republican primary in years for the three-term senator's seat. The primary election is Aug. 24.

Thousands protested the law in the politicians' hometown of Phoenix on Saturday as the congressman attended a campaign event about an hour outside town and McCain spent the day in Tucson. A pro-immigration law rally was held in Tempe.

But for McCain, the return to Arizona during Congress' district recess is a welcome opportunity to get on the ground, where Hayworth, a veteran of the Republican Revolution and a radio talk show host, has been campaigning since February when he announced a challenge against the 2008 Republican presidential candidate.

Trying to take advantage of the anti-incumbent mood, Hayworth calls himself the true conservative in the race, and has set up a chart on his website to compare his and McCain's records on core GOP values like taxes, illegal immigration, terrorism and other topics in which McCain skewed to the middle over the past few years.

Hayworth, who was ousted in 2006 in part over his ties to lobbyist Jack Abramoff, also makes frequent use of McCain's name to gin up his supporters, including issuing a message on Twitter Sunday morning about his debate on NBC's "Meet the Press."

"I'm glad that Democrats are willing to debate the issues. Now if I can only get John McCain to do the same!" Hayworth tweeted.

McCain is up by double-digits in most recent polls, but has been forced to burnish his conservative credentials in Washington, particularly after joining the late Sen. Ted Kennedy in the 2007 charge for comprehensive immigration reform that sent apoplectic Republicans and others demanding "border security first" into an all-out assault on Washington.

The opposition to the 2007 program - dubbed "amnesty" by critics -- was so great, it effectively put illegal immigration on the same rail where Social Security has sat for the past three decades, and has made any discussion of immigration reform in 2010 untenable without foremost prefacing it with calls for protecting the southern border.

McCain, however, has revived his reputation on the issue, most recently by scoring a minor moral victory last week -- getting his proposal to add 6,000 National Guard troops to the U.S.-Mexico border attached to the defense authorization bill being debated in the Senate Armed Services Committee.

He and Arizona Republican Sen. Jon Kyl have led the charge against the Obama administration's criticism of the law passed in Arizona making it a state crime to be in the country illegally.

"If you believe in representative government, when 80 percent of the American people support something, then sooner or later, even though there's a huge disconnect between Washington and the people, the Democrats will have to listen," McCain told reporters after the committee vote.

For the most part, McCain, who is considered vulnerable as long as his poll numbers hover around 50 percent, does not mention his opponent by name, though he recently took a stab at Hayworth's record of earmarks during his six terms in Congress. McCain's followers on Twitter at last count were more than 13,700 while Hayworth had just 362.

But that hasn't deterred Hayworth, who apparently is thriving on unanswered calls to debate McCain, turning his attention Sunday to Rep. Luis Gutierrez, D-Ill., one of the loudest critics in Washington of the Arizona law, and a House co-sponsor of the 2007 McCain-Kennedy bill.

Speaking on NBC, Gutierrez said the practical outcome of the Arizona law, which goes into effect in July, is going to be racial profiling, even of the most honorable Americans living in Arizona.

"It is Memorial Day tomorrow. And here is what's going to happen. There's going to be a group of guys that are going to play a soccer game. They're going to be coming home. Someone calls on the phone and says there's a disturbance, and they're going to ask somebody, 'Do you have your documents?'" Gutierrez said.

"'Well, hey, I was out playing soccer, so I didn't bring my papers with me. But by the way, I served in Afghanistan, I served in Iraq. And because of that, they expedited my citizenship papers. Can you come by my house so I can show you? Will that do?' That's what's going to happen," Gutierrez predicted.

Hayworth called that notion part of "fanciful tales" that aim to redirect the conversation to ethnic politics rather than address the crimes being committed.

"I respect the notion that freedom isn't free. Luis and I understand this Memorial Day weekend so many fought and died for that. But also, we don't breed a culture of convenience. We breed a culture of law and order. And I dare say that people are pleased to show, when called upon as law-abiding American citizens, that they're here legally," he said.

In his Washington debate, Hayworth was forced to agree with some of McCain's fight, particularly on sending National Guard to the border, and not merely in clerical and backbench positions.

"You're right. What Mr. McCain offers is first for political consumption a get-tough policy on the border, but then again, he wants to bring back amnesty," Hayworth said, noting that the conservative Heritage Foundation in 2007 estimated that the immigration reform bill proposed by Kennedy and McCain would cost $2.6 trillion in long-term retirement benefits for illegals granted citizenship.

"So much for fiscal responsibility in my opponent," he added.

Nonetheless, Hayworth will return to his state Sunday to take advantage of the tail end of the long holiday weekend, particularly since McCain will be in the state for the whole week, as the Senate doesn't return until June 7.