At the time, some Arizona Republican leaders, including U.S. Sen. John McCain, favored citizenship for some immigrants who were in the country illegally. Pearce labeled that view "treasonous," and he has steadily pushed the party to his stance by helping to oust moderates. (He endorsed McCain's rival in last year's GOP primary.)
Many Pearce proposals languished. But, bit by bit, he racked up victories.
"He's very methodical," said state Sen. Kyrsten Sinema, a Democrat. "He would start out with ideas that were outlandish, and he would do them over and over and over again. It's just a basic understanding of human psychology: If you talk about something over and over, it's not crazy."
In 2004, he wrote a ballot measure denying state services to illegal immigrants and requiring picture identification to vote, which passed easily.
A law to dissolve businesses that repeatedly hired illegal immigrants finally passed in 2007 and was signed by Democratic Gov. Janet Napolitano. (Though he's backed several low-tax measures, Pearce has had a sometimes tense relationship with Arizona's business community because of his positions on illegal immigration.)
During his legislative crusade, Pearce's son Sean, a sheriff's deputy, was shot in the stomach by an illegal immigrant accused of murder. Pearce rarely mentions his son, who survived the shooting, but in interviews he often grimly rattles off names of Arizona police officers killed or wounded by illegal immigrants.
Pearce's opponents accuse him of racism. Some tie him to white supremacist groups — he once approvingly forwarded an e-mail from one such organization, and shared the stage with a local neo-Nazi at an immigration rally in 2007. Pearce, who has Latino grandchildren, has said he wasn't aware of all the views of the racist groups involved in each incident.
His allies say the racism accusation is a smear from liberals. "What he stands for is against everything they're trying to accomplish," said Michelle Dallacroce, an anti-illegal-immigration activist.
Pearce came to national attention last year with SB 1070, which would require police to investigate the immigration status of people they have detained.
The law also contains some distinctly Pearce-like absolutist provisions — taxpayers could sue any public agency that did not fully enforce immigration laws, and anyone arrested in the state would be held until their immigration status was verified by the federal government.
Only one Republican — who was retiring — dared vote against SB 1070. Brewer signed the bill, sparking the legal challenge from the Obama administration. A judge struck down most of the law as unconstitutional.
Pearce was furious. "When you talk about jihad, that is exactly what Obama has against America, specifically the state of Arizona," he told a gathering of conservative activists in November.
Bruce Merrill, a longtime pollster and emeritus professor of political science at Arizona State University, said that although some of Pearce's immigration stands had been popular, his brand of conservatism was favored only by about 20% of the state. But Merrill noted that a tiny minority of the state votes in the primaries that control who wins elective office.
Dallacroce said she thought Pearce had helped Arizona replace California as the country's political innovator.
"Right now, as Arizona goes," Dallacroce said, "so goes the nation."