But Beck, a bespectacled 65-year-old Sunday-school teacher and former newspaper reporter, is ready to match this blitz. "It's interesting," he said. "I keep reading about the plans the other side has, and I go, check, check, check. Get people to town-hall meetings. Get people visiting the offices. Keep communicating in all the ways you communicate -- the phone calls, the faxes, the emails."

The movement in favor of immigration reform unites Democrats and Republicans, business and unions, churches and human-rights activists. More than 400 companies and groups, from Adobe to the Washington Farm Bureau, recently signed a pro-reform letter to congressional leaders. Beck's side of the immigration debate is not that kind of broad coalition. It consists of about 2 million ordinary Americans, backed by a functional, unadorned website, an email list, and a lobbying office on Capitol Hill. There are local groups here and there and some Tea Party chapters that have taken up the fight. But of the groups devoted to grassroots activism against immigration reform, "there's no question we are by far the largest," Beck said.

To Beck, this is a David-and-Goliath story -- his humble legions pitted against the well-financed campaign of the "corporate lobby," which wants more immigrants chiefly to supply businesses with cheap labor. (The Sunlight Foundation estimates that $1.5 billion has been spent lobbying for immigration reform over the last four years; NumbersUSA consists of two affiliated nonprofits with a shared annual budget of about $6.5 million, according to public filings.) To his opponents, the group's ties to white supremacism prove that it is merely a front for racist hatred, a charge Beck strenuously denies.

It is a small operation with undeniably fringe views. And yet it's not at all far-fetched to think that NumbersUSA will win this fight. After all, they've done it before.

An Unorthodox Ideology

Opposition to "amnesty" -- that is, a reform of the immigration system that allows most of the millions of current undocumented immigrants eventually to become citizens -- is generally considered a right-wing view. But NumbersUSA's roots are more unorthodox than that -- in the population-control movement that has counted environmentalists and abortion-rights activists among its allies. When Beck started the group in 1996, he was working for John Tanton, a reclusive 79-year-old ophthalmologist who lives in rural Michigan and once founded local chapters of the Sierra Club and Planned Parenthood.

Tanton has also left a long paper trail of eugenicist, anti-Semitic, and white-supremacist views. According to a report by the Southern Poverty Law Center, Tanton has a record of "fretting about the 'educability' of Latinos, warning of whites being outbred by others, and publishing a number of white nationalist authors." He has also "corresponded with Holocaust deniers, former Klan lawyers and the leading white nationalist thinkers of the era." At the same time, he has raised millions for the network of organizations he founded to push his agenda -- primarily stopping immigration. NumbersUSA is the grassroots-activism arm; there's also the Center for Immigration Studies, a D.C. think tank, and the Federation for American Immigration Reform, an activist organization labeled a hate group by the SPLC.