By all accounts, the Heritage Foundation study that would have been the conservative media's cudgel to defeat comprehensive immigration reform a second time is all but rotting in the ground, buried under accusations of anti-immigrant and race-based bias. Beyond losing all credibility, its conclusions that reform will total at least $6.3 trillion have been exposed as bogus by the most respected conservative groups and immigration experts.

In fact, the only people left willing to defend Heritage are part of an anti-immigrant movement that mainstream conservatives are reportedly trying to confine to the fringe. But that hasn't stopped right-wing media outlets from amplifying these voices in an effort to tank a bipartisan immigration proposal currently being debated in the Senate.

In a column published by WND and Human Events, Pat Buchanan defended Heritage and Jason Richwine, the co-author of the study whose writings that race and intelligence are genetically linked forced his resignation.

As The Washington Post reported, Richwine wrote in his Harvard doctoral dissertation that Latinos are undesirable as immigrants because, he argued, they have lower IQs than white Americans. Other controversial comments by Richwine surfaced, including his claim that “psychometric testing has indicated that at least in America, you have Jews with the highest average IQ, usually followed by East Asians, and then you have non-Jewish whites, Hispanics, and then blacks.”

After citing a series of examples he argued showed “greater 'underclass behavior' among Hispanics,” Buchanan warned that by granting legal status to the country's population of undocumented immigrants -- most of whom are from Latin American countries -- “America in 2040 is going to look like Los Angeles today.” He added: “America in 2040 will be a country with whites and Asians dominating the professions, and 100 million Hispanics concentrated in semiskilled work and manual labor.”

Never mind that once granted legal status, immigrants see an immediate increase in wages and an even bigger increase over time as they invest more in education and jobs training.

In his criticism of the Heritage study, American Action Forum president and former Congressional Budget Office head Doug Holtz-Eakin explained to a congressional committee:

You have to be very careful about the assumptions you make. We know that the labor force participation of first-generation immigrants is higher than the native-born. If you go to the second generation where people often worry about the take-up of public programs -- there are more college degrees in the second-generation immigrants than the native-born. There are more advanced degrees, graduate degrees. There's higher rates of labor force participation among those. So it's not the case that program participation is higher than in the native born population on the whole.

Buchanan has repeatedly stated that the influx of undocumented immigrants is “not immigration” but “an invasion of the United States of America.” He has warned that America is “committing suicide” while “Asian, African, And Latin American children come to inherit the estate.” He once argued against immigration reform by citing the views of white nationalists.

This is the core group of people who have joined Buchanan in defense of Heritage and Richwine's scholarship. It is basically a “who's who” of the anti-immigrant extremist establishment that continually argues against non-white immigrants and groups:

Former National Review contributor John Derbyshire -- forced to resign from the publication after he penned a column advising white parents to teach their kids to be wary of black people and has likened the high percentage of Hispanic students in an Iowa town to “an invasion” -- wrote that “everything” Richwine said in his thesis “is true, and buttressed by facts.”

Peter Brimelow -- founder and editor of VDARE.com who had a regular column for News Corp.-owned financial site MarketWatch (he hasn't written anything since September 2012) -- agreed that the “facts about the differing average IQ levels of the various post-1965 immigrant streams have been settled science for many years.” He called Richwine's resignation “the most depressing thing that has happened in American politics for many years.”

Charles Murray -- the discredited author of The Bell Curve, which served as a guide for Richwine's thesis as it argued that the reason minorities are over-represented in the lower classes is because they are less intelligent than their more affluent white counterparts -- wrote at National Review Online that Richwine's thesis “showed exactly what he said they showed: mean IQ-score differences between Latinos and non-Latino whites.”

Jared Taylor of American Renaissance -- described as a "white supremacist journal" by the Anti-Defamation League -- lamented Heritage's “act of cowardice” for firing someone “saying something that is not only true, but that everyone knows to be true.” Former NRO contributor Robert Weissberg was fired for speaking at the magazine's annual conference.

Richard Spencer -- founder of white nationalist site Alternative Right and president of the National Policy Institute, who has said, “There are races who, on average, are going to be superior” -- wrote that “race and heritability” are “perhaps the two most consequential factors in any policy or social analysis.”

The Southern Poverty Law Center has identified VDARE, American Renaissance, Alternative Right, and the National Policy Institute as “white nationalist groups.” MSNBC host Rachel Maddow highlighted the connection between Richwine and Alternative Right in a recent segment.

NumbersUSA, the Federation for American Immigration Reform (FAIR), and the Center for Immigration Studies (CIS) -- groups founded by nativist John Tanton, the modern architect of the anti-immigration movement -- have maintained the study's accuracy while not addressing the Richwine controversy.

However, Richwine is undeniably tied to these nativist groups: During his time at Heritage, he spoke at two events for The Social Contract Press, which is published by Tanton.

In an article highlighting growing concerns among conservatives about who they're relying on to support their opposition to immigration reform, BuzzFeed reported that they worry that “opponents have allied themselves with pro-abortion environmentalists, xenophobes and other questionable scholars” :

[A] senior official at the conservative reform supporting group was quick to draw a line between CIS and its affiliated groups and Heritage, but said it was time for fresh scruitiny. “I wouldn't lump Heritage in with CIS, NumbersUSA, and FAIR -- Heritage is actually a productive member of the conservative movement,” he said. “The others are population control zealots who dislike newborn babies just the same as they dislike immigrants. But perhaps those using Tanton talking points to inform their views on this issue should scrutinize the founding motivations of these anti-immigration groups.”

Similarly, Mario Lopez, president of the conservative Hispanic Leadership Fund, told BuzzFeed: “There are more people on the right this time who understand exactly who those folks are and what their views are and how politically damaging it is to be in bed with folks whose fundamental interests lie in direct conflict with conservative principles.”

While America's Voice founder Frank Sherry explained that the Heritage blowback “will force opponents to distance themselves from the ugly influence of white nationalism that has infected the opposition for too long or marginalize it further for not doing so,” the nationalist ideology is still perfectly acceptable inside the conservative movement and the right-wing media.

Heritage has distanced itself from Richwine's rhetoric, but has stood by the study's flawed conclusions. A wide swath of conservative groups, however, have repudiated the findings, including the Cato Institute, the American Enterprise Institute, Americans for Tax Reform, and the American Action Forum.