The co-author of a conservative think tank's report accusing Latino immigrants of having a "substantially lower" average IQ than white Americans resigned on Friday.

According to The Washington Post, the Heritage Foundation confirmed that Jason Richwine left the organization in the wake of bipartisan criticism of the report, which said that giving the country's 11 million undocumented immigrants "amnesty" in the form of a route to become U.S. citizens would cost the country $6.3 trillion in social services and lost workplace productivity.

Politico reported that, while Heritage acknowledged his departure, the foundation was standing by the report's cost estimate for immigration reform. The foundation is also reportedly bringing in an outside public-relations group to further address the flap created by Richwine's report.

"Jason Richwine let us know he's decided to resign from his position," the group said in a statement. "He's no longer employed by Heritage. It is our long-standing policy not to discuss internal personnel matters."

Opposition to the report grew louder once Richwine's 2009 doctoral dissertation at Harvard came under closer examination.

"The average IQ of immigrants in the United States is substantially lower than that of the white native population, and the difference is likely to persist over several generations," Richwine wrote, an argument he would revisit for the Heritage report. "The consequences are a lack of socioeconomic assimilation among low-IQ immigrant groups, more underclass behavior, less social trust, and an increase in the proportion of unskilled workers in the American labor market."

Richwine also proposed using "High-IQ" immigrants to address those issues in the U.S., but rebranding the process as a "skills-based" policy so as to avoid complaints.

Not only did other conservatives knock the Heritage report for, among other things, failing to consider immigrants' ability to become citizens who do not rely on social services, but Congressional Hispanic Caucus head Rep. Rubén Hinojosa (D-TX) called it a mark against the conservative community.

"The Heritage Foundation has always been a stalwart of conservatism, but this is common-place, ugly racism and xenophobia dressed up in economic hyperbole," Hinojosa said. "I urge everyone in the conservative community to step up and speak out against this disgraceful, so-called report."

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