Whether illegal immigration will be decisive in the presidential race this summer and fall is unclear. The issue has been among the top three concerns for voters in Republican presidential nomination contests, along with Iraq and the economy, according to exit polls. The Iraq war and the economy are also dominant among Democratic voters, but healthcare has emerged as the third key concern.

Indeed, Republican candidates are likely to focus on McCain’s military service and record on the Iraq war, two things that have kept him in good stead among conservatives. Some are blunt, however, about their opposition to his immigration stance.

“I fully support Sen. McCain; he is an American hero,” said Jim Ogonowski, the Massachusetts GOP Senate candidate who nearly won a special 2007 House race by stressing illegal immigration. “That’s just one particular issue where I will stand up and tell him what I believe.”

Despite the long GOP odds of that race, Ogonowski and others will at least keep the immigration debate alive by running for Congress, according to Tancredo. In an interview with The Hill, Tancredo decried the fact that McCain, Sen. Hillary Rodham Clinton (D-N.Y.) and Sen. Barack Obama (D-Ill.) have each supported a pathway to citizenship for illegal immigrants.

Tancredo, who is not running for reelection, said that Republicans in the House, such as Reps. Brian Bilbray (Calif.) and Steve King (Iowa), and perhaps Barletta will need to serve as a counterweight to the next president.

“We’ll have to look at the Congress as the next line of defense,” Tancredo said.

The last line of defense is state government, said Tancredo, who wouldn’t rule out a future run for governor in Colorado.

McCain’s nomination won’t deter the staunchest illegal immigration opponents, said Roy Beck, president of NumbersUSA, an advocacy group opposing amnesty. He said that the hard line taken by House Republicans on illegal immigration has forced some Democrats and McCain to shift their positions. Beck pointed out that freshman Democratic Rep. Heath Shuler (N.C.) has backed a bill requiring companies to verify that their workers are here legally. Beck also notes that McCain now tells voters that the government needs to secure the borders before deciding what to do with the approximately 12 million immigrants in the country illegally.

“What you’re going to see is him sidestepping, see him dodging [the illegal immigration issue],” Beck said. “That won’t be a case of Republican congressional candidates seeming to be at odds with the presidential candidate.”

Just weeks after announcing his candidacy in February, Barletta has already taken the issue of immigration to Kanjorski in a way McCain can’t.

Barletta has tied many problems in his district — crime, increased local taxes and a lack of jobs — to illegal immigration, prompting Kanjorski to downplay the effect of the issue. Kanjorski also noted that Barletta has received an endorsement from former Ku Klux Klan leader David Duke and was quoted in another newspaper saying, “What David Duke was to civil rights, my opponent has done that with immigration.”

Added Kanjorski: “He’s used that issue the same way Duke used the civil rights issue.”

Kanjorski apologized for his remarks last week, giving Barletta the chance to stress the impact he has seen in his city — and deflect any complications stemming from McCain’s stance.

“The problems of illegal immigration are on the streets and in the neighborhoods in the local communities,” he told The Hill. “We’re the ones that bear the burden of the cost.”