"This is an issue that in every election the Republicans believe is going to be the keys to the kingdom, and it never performs for them politically," said Simon Rosenberg, founder of NDN, a Democratic advocacy group and think-tank.
"For most Americans this is a secondary or tertiary issue. What they want their politicians to address at the federal level is the economy, healthcare ... issues that are actually more important to them," drawing on polling to back up that argument.
Those facing potential fallout from the legal challenge are Arizona U.S. Representatives Ann Kirkpatrick, Harry Mitchell and Gabrielle Giffords, who are all seeking re-election in congressional districts that already lean Republican, analysts say.
"Those three races are Ground Zero for me," said Mark Jones, a political scientist at Rice University, citing their vulnerability. "You have three incumbent Democratic members of Congress who are identified with President Obama and Nancy Pelosi ... they are eventually part of the power structure that is challenging the Arizona legislation."
While the controversy is unlikely to severely damage Democrats, neither will it be all positive for Republicans.
It has energized some Republican primary races - notably Ms. Brewer's run for the party's gubernatorial nomination on August 24. A Rasmussen Reports poll in June showed her opening up a 49 point lead over her nearest rival, Dean Martin, with whom she was tied as recently as March.
But embracing the law carries greater risks for the GOP with Hispanics, the country's fastest-growing minority and an increasingly hefty voting bloc which turned out 2 to 1 for Mr. Obama against Republican candidate and Arizona Senator John McCain in 2008.
"I just don't like that law," said Mexican-American Susan Islas, a Hispanic and independent who toted a placard at a rally to protest the law in Phoenix last week. "We will remember in November who to vote for and who not to vote for."
Signs of that discomfort are already being felt.
In California, billionaire gubernatorial candidate Meg Whitman had a divisive primary battle with Steve Poizner over which candidate would do the best job of stopping illegal immigration. She has since had to backtrack as she fights for the Hispanic votes she will need if she is to clinch victory over her Democrat rival Jerry Brown
Using her deep pockets, she is running Spanish-language ads and billboards to distance herself from the Arizona law, and has said she would have voted against Proposition 187 in 1994, an earlier Republican measure that sought to deny services to illegal immigrants in the state.
"Latinos have not been voting for Republicans because they perceive it's a white man's party that doesn't have any respect for them. Meg Whitman has to create an atmosphere of, 'Hey, I appreciate your needs,"' said Allan Hoffenblum, Republican political analyst and publisher of the California Target Book. "She has the money to do it and do it early."
In Texas, Governor Rick Perry, meanwhile, is walking a fine line over the law. He has said it "would not be the right direction for Texas," while appeasing his base by supporting a brief by the state's attorney general, Greg Abbott, opposing the Mr. Obama administration's challenge to the law.
While the law has put a match to the immigration debate, sending a blaze through some of the Republican conservative base, analysts and advocates say the party will likely try to douse it before heading into the 2012 presidential cycle.
"Smart Republicans know that, if they are going to retake the White House, they are going to have to win approximately 40 percent of the Hispanic vote," said Frank Sharry, the founder of America's Voice, a group that supports comprehensive immigration reform.
"Going into the presidential cycle, you're going to have a lot more Republicans speaking up and going 'whoaa!' "Report Typo/Error
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