He keeps grade cards for every member of Congress, deploys 3 million activists to blast lawmakers with anti-immigration-reform telephone calls, faxes and emails, and runs a website where his followers have called undocumented immigrants "criminal invaders" and "wolves at the door."

But for Roy H. Beck, the 66-year-old driving force behind a small but powerful organization that has helped scuttle every effort at an immigration overhaul for nearly two decades, the fight is only beginning. Over the next year, his goal is to cut off funding for President Barack Obama’s executive actions that have shielded 5 million people from deportation and will allow many of them work permits.

"There’s a good chance that we’ll roll back a good share of this," Beck said in a recent interview in his Rosslyn, Virginia, office, a mostly threadbare space with sweeping views of the Potomac River and the Capitol dome. "We did as much as possible to make immigration radioactive in as many places as possible."

As the founder and president of NumbersUSA, Beck has 35 staff members and an annual budget of about $10 million compared with a coalition of immigrant groups that spent $1.5 billion from 2008 to 2012 lobbying for an array of immigration changes, according to an estimate by the nonpartisan Sunlight Foundation. But what Beck lacks in resources, he makes up for in impact.

Beck and his group "have succeeded in thwarting the passage of comprehensive immigration reform by generating popular anger on the right that overwhelmed mainstream Republicans," said Frank Sharry of America’s Voice, an advocacy group pressing for such an overhaul.

At the very least, immigration advocates say, they will have to fight the grass-roots uproar that Beck has fueled.

Beck, a former environmental journalist who once worked at The Grand Rapids Press and The Cincinnati Enquirer, said he did not feel the rage toward immigrants that he is able to marshal in others. He voted for Obama in 2008 and is consistently described by his critics as genial and nonconfrontational. But he says that the rise in immigration levels is destroying the United States — both the environment and employment opportunities for the working class — and is angry at what he considers complicity by the government on the immigrants’ behalf.

While the country once admitted about 250,000 legal immigrants annually, he said, the number has ballooned to 1 million, with another roughly 700,000 entering illegally — the equivalent of adding another Philadelphia each year. Beck is pressing to cut legal immigration to 500,000 people a year.

"This has nothing to do with the immigrants themselves," Beck said. "But are the people who are here illegally more important than the Americans, the people of this national community, who have absolutely been robbed of their dignity?"

Despite his disclaimers, Beck’s critics say he is pushing a xenophobic agenda and is the benign face of a racist movement.

"He’s played footsie with extremists all along," said Heidi Beirich, the director of the Southern Poverty Law Center’s Intelligence Project, which tracks hate groups.

Even as she described Beck as a "completely nice guy," Beirich said that "in a way, what Beck does is, he provides cover for the bad guys."

The criticism stems from Beck’s connection to John H. Tanton, a Michigan ophthalmologist who helped start and finance NumbersUSA and has nurtured two other groups, the Federation Against Immigration Reform and the Center for Immigration Studies, which share Beck’s commitment to reducing immigration.

Beck described him as "one of the grand environmental leaders," but Tanton has also been accused of pushing a white nationalist agenda, and he once wrote of his fear of a "Latino onslaught."

Beck said that his group had been independent of Tanton for a dozen years, and he went out of his way to deny charges of racism.

He has a "No to Immigrant Bashing" section on the NumbersUSA website urging civil discourse, and said he filtered out user comments that contain overtly racist terms.

He has also posted a photograph of Barbara Jordan, an African-American former Texas congresswoman and civil rights leader who was the chairwoman of an immigration commission he advised in 1996, in part, Beck said, to ward off racist members. Jordan died in 1996.

"If you’re a white supremacy group, that’s sort of a signal to you that, ‘This is not our group,’" Beck said.

Tax disclosures filed in 2013 show that NumbersUSA received about $4.5 million from the Colcom Foundation, a Pittsburgh-based organization founded by Cordelia Scaife May, the Mellon banking heiress. The foundation says it works to combat overpopulation; the Southern Poverty Law Center says the foundation funds hate groups with "nativist" missions. The foundation’s vice president of philanthropy is John F. Rohe, a Tanton loyalist and biographer.

NumbersUSA, Beck said, has "always stayed away from cultural issues."

From his earliest days, Beck focused on numbers.

Now the father of two adult sons, he was raised in Marshfield, a town of 2,500 in Missouri’s Ozarks, where he delivered milk and collected cans to make pocket money. After attending journalism school at the University of Missouri, Beck became interested in immigration while covering the birth of the environmental movement in the late 1960s, as concern grew about the consequences of population growth on natural resources.

Disillusioned when he thought immigration was not receiving sufficient attention, he left journalism in the 1990s to write books, and later decided to start NumbersUSA.

He began with a video, recorded on VHS tape in 1996, in which he used a huge container of colored gumballs to illustrate the billions of people living in developing nations, and a small glass snifter to portray the United States, taking in millions more immigrants, one gumball at a time.

The gumballs are still in his office, but on a recent afternoon, he left them behind and instead took PowerPoint slides to make his arguments to a group of Grinnell College students spending a semester in Washington.

"At the end, unless somebody’s watching the numbers, you end up with a problem," Beck told the group.

"It sounds horrible, doesn’t it?" Beck conceded of his group’s position that immigration should be sharply curtailed and strict new workplace screenings instituted, so any undocumented worker is immediately laid off.

"People say, ‘Boy that’s really mean – it’s so mean – because you’re making that person who has a job lose a job,’" Beck told his young audience. "And yet, as long as they’re in that job, what’s the meanest thing of all? The Americans that don’t have that job."

© 2014 The New York Times Company