The year 2005 was a watershed year for the anti-immigrant movement. In April, the Minuteman organization was launched with an armed civilian "border watch" in Arizona. Although President Bush described the Minutemen as "vigilantes," the HIRC defended and praised the group in a "Field Report" entitled "Results and Implications of the Minuteman Project." In a separate statement, Caucus member Phil Gingrey (R-Ga.) said, "The Minuteman Project is a shining example of how community initiative and involvement can help make America a safer, better place to live." The sentiment was echoed by the eight other congressmen cited in the press release.

Also in 2005, Tancredo personally introduced a resolution proposing that the Constitution be amended to establish English as the "official language," another resolution "recognizing the importance of Western civilization," legislation to enhance border enforcement and curtail H1-B visas, as well as several amendments aimed at changing federal enforcement policies. He introduced eleven different measures in all, none of which succeeded. But Tancredo had raised the flag of the anti-immigrant movement within Congress. By August, the Caucus registry had grown to 82 members of the House.

By December of that year, the House passed H.R. 4437, known popularly as the "Sensenbrenner Bill." James Sensenbrenner, a Republican from Wisconsin's 5th District, was first elected to congress in 1978, and was chairman of the House Judiciary Committee at the time. He was not then, and is not now, a member of Tancredo's Immigration Reform Caucus. Nevertheless, H.R. 4437 was widely regarded by both immigrant rights activists and moderates as an unnecessarily harsh bill that was unlikely to pass in the Senate. It would have turned undocumented immigrants into felons (current law considers this violation a misdemeanor) and thus make them ineligible for citizenship in the future. It would have also criminalized anyone who gave them assistance of any kind, including providing them with simple social welfare or routine medical services. The bill also called for the construction of 700 miles of fencing on the southern border.

The debate in Congress became so vicious that even conservatives were forced to comment on its racism. "Some anti-immigrant Republicans are guilty of demagoguery and racism," one Republican governor, Mike Huckabee from Arkansas, told the press.

Despite its punitive character, Sensenbrenner's Bill was still not considered tough enough for members of the HIRC. Rep. Nathan Deal (R-Ga.), for example, tried unsuccessfully to amend the bill to include a provision that would have denied citizenship to those children of undocumented workers who were born on U.S. soila clear violation of the Constitution's Fourteenth Amendment.13

Further, Rep. Virgil Goode (R-Va.) and Rep. Duncan Hunter (R-Calif.) proffered a comprehensive measure of their own as a substitute for H.R. 4437. Hunter is another of the HIRC members currently running in the Republican presidential primaries.