The Heritage Foundation was supposed to be where Jim DeMint expanded his influence. Drawing on the lessons of his term-and-change in the United States Senate representing South Carolina – DeMint stunned Washington by resigning on January 1 to take the helm of the influential, nonprofit think tank – he would use the new post to shape the national debate on a whole host of issues, and bring his brand of right-wing conservatism to bear on the Republican Party.

If moving from the Senate to a think tank seems like a step down, consider the frustrations of working in a legislature. You need to build compromise with other lawmakers, defer to party leaders, make disclosures on what you raise and what you spend, and satisfy constituent problems. It takes a lot to do this for six years, much less twelve. And given the Supreme Court’s decision in Citizen’s United—which shifted money and power from elected officials to independent groups—it’s no surprise that DeMint decided to step up from the Senate to Heritage .

But less than a week after the disastrous rollout of the Heritage case against immigration reform – effectively his big debut in his new role – it seems that DeMint may have made a big miscalculation.

Of the issues where DeMint could flex his muscles as president of Heritage, immigration wasn’t a bad choice. After all, it was only six years ago that Heritage Foundation—and DeMint, in the Senate—led the fight against George W. Bush’s proposal for reform, which—like the current “Gang of Eight” bill—contained provisions for border security, a guest worker program, and a path to citizenship. At the time, Heritage attacked the Bush proposal as “amnesty” and issued reports warning that it would draw 100 million new immigrants and vastly expand the welfare rolls. When the bill failed to overcome a filibuster in the Senate, DeMint declared, “the American people won today.”

With their report last week putting a huge $6.3 trillion price tag on immigration reform and again calling any attempt at reform tantamount to “amnesty,” DeMint and Heritage were trying for an encore performance.

The circumstances of 2013, however, are considerably different from the ones of 2007. Then, the Republican Party was convinced of its ability to win elections sans significant support from minorities, and Latinos in particular. Now—after President Obama won reelection with a minority of white voters but an overwhelming majority of blacks, Latinos and Asian Americans—many Republicans are convinced they need to make sustained outreach to minority communities, and Hispanics in particular. A GOP push to pass comprehensive immigration reform, they argue, is a necessary move in that direction and a way to open doors for further conversations.

Which is why, after Heritage dropped its report at the beginning of last week, a whole host of pro-reform Republicans went after it in a fierce backlash. “The Heritage Foundation document is a political document. It’s not very serious analysis,” said former Mississippi governor Haley Barbour. Likewise, Arizona Senator Jeff Flake—a co-sponsor of the immigration bill—challenged the study’s assumptions. “Here we go again. New Heritage study claims huge cost for Immigration Reform. Ignores economic benefits. No dynamic scoring,” he wrote on Twitter.

But it wasn’t until the Washington Post revealed the racist ideology of one of the report’s authors, Jason Richwine, that things really began to unravel for DeMint and Heritage. Within a day of the revelation, reporters had combed through Richwine’s Harvard dissertation—where he argues that the IQ of Latino immigrants is too low for them ever to assimilate—and his history. In 2008, for example, Richwine had given a presentation at the American Enterprise Institute where he explained the racial hierarchy of intelligence: “Decades of psychometric testing has indicated that at least in America, you have Jews with the highest average IQ, usually followed by East Asians, then you have non-Jewish whites, Hispanics, and then blacks.”

Not only did this cause a public relations crisis for Heritage—which found itself pushing a report authored in part by a modern-day phrenologist—but it gave Republican proponents of immigration reform an easy way to dismiss the full report. By giving Richwine a platform and making him one of the prominent voices against immigration reform, Heritage has tarnished its cause; now, it’s even more associated with prejudice and nativism. Immigration reform advocates have gained the moral high ground and a new sense of urgency—they need to pass a bill to show Latino voters that racial animus has no place in Republican politics.

Richwine “decided to resign” on Friday, according to Heritage, but the damage has already been done. Far from sparking a tide of conservative opposition to the Senate’s immigration reform bill, DeMint has inspired proponents to fight harder. By pushing a questionable study and employing an outright racist, DeMint has accomplished the exact opposite of what he set out to do.

None of this means Heritage is out for the count. On other issues—like taxes and spending—the Foundation will continue to influence the anti-government wing of the Republican Party, which at this point, is just the Republican Party. Indeed, the expansion of Tea Party conservatism is one of Jim DeMint’s gifts to American politics.

But on immigration reform, the influence he thought he might gain by joining Heritage hasn’t materialized. His cynical decision to leave elected office and exercise power from a different perch has backfired, and on this issue, left him a more marginal figure than he ever was in the Senate.