If illegal immigration is going to play a defining role in any one House race this year, it will be in Pennsylvania's Eleventh District, where incumbent Democrat Paul Kanjorski is facing a challenge from Republican Lou Barletta, the mayor of Hazelton who has made a name for himself as an anti-illegal immigration activist. Both candidates are focusing heavily on the issue, but Barletta, beloved by national anti-immigration foes, has gone a step farther and is calling out his own party's presidential nominee.

Barletta garnered attention several years ago with a bid to impose penalties on landlords who offer their properties to illegal immigrants and businesses who employ them. He has become a staple on conservative talk shows around the country, featured on shows hosted by Lou Dobbs and Sean Hannity, among scores of others. After losing his 2002 bid against Kanjorski, Barletta is trying again to represent the district, several hours north of Philadelphia that stretches from the New Jersey border toward the middle of the state.

His focus on immigration and his national profile have gotten Barletta plenty of media coverage. His announcement drew dozens of cameras and reporters as he promised to take his fight on the issue to Washington. Barletta has even invited John McCain, Barack Obama and Hillary Clinton to his home town to discuss ways to stop illegal immigration, The Hill's Aaron Blake reported today.

While Obama and Clinton have yet to respond, McCain's campaign wrote back and said thanks, but no thanks. That prompted an angry response from Barletta. "While I commend Sen. McCain for being the first to respond to my invitation, I am very troubled by his decision to decline my offer," the GOP candidate said in a statement. A letter to Barletta from the McCain campaign said they did not see an opportunity to get to Hazelton.

McCain, no friend of the anti-illegal immigration hardliners who populate much of the GOP's base (as well as his home state's Republican Party), has recently made news by suggesting that it was those views that contributed to his party's loss of a Congressional seat earlier this month. McCain told National Public Radio that "anti-immigrant" views, as he characterized them, were the reason Republican candidate Jim Oberweis lost his race to replace Dennis Hastert in Illinois.

Barletta is unlikely to let the issue drop. He said the invitation to all three top candidates "will remain open, because illegal immigration is a problem that is not going away before Election Day, or anytime soon." For McCain, the ire of a prominent immigration hardliner, and a member of his own party, is something he doesn't need.

If Barletta can't overcome Kanjorski and McCain comes close or wins his own battle, maybe the GOP will rethink their approach to illegal immigration. If the opposite happens, or if McCain loses a significant portion of the Republican base, watch for immigration hardliners to try and reassert themselves as a dominant force in the party moving forward.

While few races can really be said to have been determined based on illegal immigration, the Kanjorski-Barletta matchup will truly determine if immigration moves a large number of votes, or if it's even a partisan issue at all.