Republican state Senator Russell Pearce, a long-time fixture in Arizona politics but until recently a virtual unknown elsewhere, never expected to singlehandedly shake up national politics, let alone get under the skin of the White House.
"Nobody could have guessed the impact it would have," Mr. Pearce said of the divisive law he crafted to crack down on illegal immigrants in his state - of which there are nearly half a million. "Who could have guessed that I would have pissed off the president of the United States?"
A 63-year-old father of five and former lawman who worked for the local Maricopa County Sheriff's Office for 23 years, Pearce is clearly reveling in the political shockwaves he has created. He says he is also pleased to have called attention to what he and many other Americans consider misguidedly lenient policies toward illegal immigrants.
As a result, Arizona - the desert state that provided presidential candidates in Barry Goldwater and John McCain - has become a crucible for policy on immigration, an issue that crystallizes popular anger ahead of the midterm congressional vote in November.
The state's controversial law goes into effect Thursday, barring successful legal challenges. It will make it a crime to be in the country without proper documents. Local backers say the legislation's intent is to curb the smuggling of both humans and drugs over the state's porous border with Mexico.
It also requires state and local police officers to check the immigration status of anyone they suspect is unlawfully in the country, even during routine traffic stops. Critics say that this will inevitably result in widespread harassment of Hispanic or Hispanic-looking Americans.
Even so, polls show the Arizona approach is supported by a solid majority of Americans - a Rasmussen Reports poll in late May found 55 per cent of respondents nationally would like a similar law in their own state. Consequently, some political experts say President Barack Obama's steadfast opposition to it will likely help galvanize grass-roots Republican groups.
More significantly, the new law appears to be inspiring copycat efforts in at least 20 other states. That is in addition to the five states that have already introduced similar legislation this year.
As wedge issues go, however, this one may well end up languishing in the desert. Many political analysts say illegal immigration is unlikely to be a deciding factor in all but a handful of contests - mostly in Arizona itself.
And the eventual backlash against the measure, experts say, could prove severe for its champions, alienating an increasingly affluent Hispanic electorate once considered a potential conservative goldmine for the Republican Party.
Mr. Pearce has been working for years on state measures to curb illegal immigrants. An earlier law he championed that ultimately passed required employers to verify their workers using a federal computer system dubbed "E-Verify." That one was passed in 2007.
With conservative allies in the state legislature - where Republicans control both the House and Senate - he crafted the law with input from the Federation for American Immigration Reform, an organization that pushes for restrictions on immigration and has supported a raft of state and city ordinances across the country.
As the legislation took shape this year, Mr. Pearce got together with then-Maricopa County Attorney Andrew Thomas and consulted University of Missouri-Kansas City School of Law professor Kris Kobach. In the words of Kobach, the two sought to make the bill, known as SB 1070, a "bullet-proof law that would withstand any and all changes." They knew the legal challenges were coming.
The bill also needed the political stars to align to become law, and in a strange twist, Mr. Obama himself made it possible. Before she went to Washington in January of last year as Mr. Obama's Homeland Security secretary, Arizona's former Democratic Governor Janet Napolitano was quick to veto many of the Republican-dominated Arizona legislature's proposals, setting a state record for vetoes with 180 proposals tossed out over seven years in office.
Her Republican Secretary of State, Jan Brewer, stepped up to fill her shoes, and now the conditions were altered. At an April 23 ceremony in the state capitol, she signed the toughest immigration bill in the United States into law - a law that seeks to drive an estimated 460,000 illegal immigrants out of the state.
The day the law was enacted by Ms. Brewer, Mr. Pearce stood at the back of the room at the state capitol that afternoon, reluctant to steal her thunder but quietly elated. "I felt like a player that just scored in the final five seconds of a good basketball game," he said. "I was excited, I'd worked on this for years."
Since then, his phone has not stopped ringing. He gets perhaps a dozen media requests a day, including calls from reporters from Spain, Britain and Germany anxious speak to the man who has forced a national debate on immigration and fanned conservative embers smoldering in the Republican Party.
He has also been dubbed a racist by critics, who point out that both the number of illegals flocking across the border as well as crimes has been declining over the past several years. Opponents of the law also note that illegal immigrants mostly work in low-paid jobs on farms, in construction and in the hospitality industry - oftentimes in jobs that legal residents have long shunned.
The law has sparked interest in Republican-controlled state legislatures around the United States.
Among them is Utah, where Republican Representative Stephen Sandstrom recently took a daylong trip to the Mexico border with Mr. Pearce and other lawmakers and staff. They toured a stretch of the dusty desert strip, marked by an incomplete and much criticized steel border fence, speaking to Border Patrol agents.
Back home in Utah, Mr. Sandstrom says he will be introducing similar legislation in coming weeks, setting the process in motion by introducing it in committee in late August or early September at the latest.
"There's a groundswell of support for this," said Mr. Sandstrom, who has pushed anti-immigrant legislation for the past four years. "I think it took until this year for the people of Utah to say enough is enough. ... it's going to pass; there's no doubt in my mind about that."
Republicans in Utah are not the only ones keen on copying Arizona. The National Conference of State Legislatures said that five other states - South Carolina, Minnesota, Pennsylvania, Michigan and Rhode Island - have introduced Arizona-style immigrant legislation so far this year. And there are reports that lawmakers and other officials in as many as 20 states - Mr. Pearce puts the number at 34 - are poised to push for similar measures after the summer recess.
But it will be a legal slog.
Arizona is currently fighting lawsuits from the U.S. Justice Department and six other plaintiffs, including civil rights and advocacy groups. If U.S. District court Judge Susan Bolton does not dismiss them all, the legal battle could drag on for years.
"It's going to depend a lot on what happens in Arizona," said Ann Morse, program director for the NCSL's Immigration Policy Project. States "don't want to spend what little money they have tied up in the courts." she said.
Amid the street protests against the measure in Phoenix last week, President Obama's Justice Department lawyers launched their challenge to the state law, and the political topology was established.
"This issue is way bigger than immigration. It is Obama overreaching," said business student Bryan Berkland, 25, struggling to make himself heard over chants and beating drums outside U.S. District Court in Phoenix Thursday.
"It's the federal government overstepping its bounds," added Mr. Berkland, an independent who said Mr. Obama's challenge would clinch his vote for the Republicans.
But while the law and the administration's measures to counter it may energize some voters, analysts say illegal immigration is unlikely to become the decisive issue in any of the congressional districts that are coming into play next fall, except possibly in a handful of Arizona House races.
"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!' "