Just before Congress left for its annual summer recess at the end of July, House Speaker John Boehner announced that the House Republicans would not pass legislation addressing the issue of immigration reform this year. It was a blow to those who had hoped that the House would vote on the bipartisan immigration reform bill passed by the Senate in late June, but unsurprising to anyone who had seen the numerous conservative revolts against Boehner’s attempts to wrangle his caucus on the issue.

The inability of House Republicans to find consensus among their members is all the more puzzling, given Americans’ high levels of support for comprehensive immigration reform. More than 6-in-10 (62 percent) Americans favor providing a way for immigrants who are currently living in the United States illegally to become citizens provided they meet certain requirements, while 17 percent support allowing them to become permanent legal residents but not citizens. Fewer than 1-in-5 (19 percent) of Americans favor a policy that would identify and deport all immigrants living in the United States illegally. Even a majority (51 percent) of self-identified Republicans favor a path to citizenship for immigrants living in the country illegally.

In an election year, why would the House Republicans oppose the passage of legislation that many of their constituents support? Writing at the Brookings Institution’s blog, Christopher S. Parker, an associate professor of political science at the University of Washington, argues that the House GOP isn’t animated by conservative doctrine. Comprehensive immigration reform would save the country hundreds billions of dollars during the first decade of implementation alone, a result that aligns with the core conservative principle of fiscal responsibility.

House Republicans “aren’t motivated by true conservatism,” Parker writes. “Rather, they represent constituencies haunted by anxiety associated with the perception that they’re “losing their country” to immigrants from south of the border.” These constituencies are, of course, the Tea Party.

Parker’s hypothesis is borne out convincingly by Public Religion Research Institute’s latest survey on immigration reform. Among political groups, the Tea Party stands out in its opposition to any kind of amnesty for undocumented immigrants: Fewer than 4-in-10 (37 percent) Americans who are part of the Tea Party movement favor allowing immigrants living in the U.S. illegally to become U.S. citizens, while 23 percent favor allowing them to become permanent legal residents but not citizens. Notably, 37 percent favor a policy that would identify and deport all immigrants in the U.S. illegally, the highest among all partisan groups.

Moreover, Americans who identify with the Tea Party hold much more negative views about immigrants’ economic and social impact on the U.S. than Americans who are outside the movement. Americans who identify with the Tea Party are substantially more likely than Americans who are not part of the Tea Party to agree that immigrants today are a burden on our country because they take our jobs, housing, and health care (57 percent vs. 32 percent). Nearly two-thirds (65 percent) of Tea Party-identified Americans believe that illegal immigrants hurt the economy by driving down wages, compared to only 43 percent of Americans who do not identify with the movement. Finally, nearly 6-in-10 (58 percent) members of the Tea Party say that the growing number of newcomers from other countries threatens traditional American customs and values.

Given the high-profile primary challenges that establishment Republicans have faced at the hands of Tea Party candidates, it’s easy to understand why immigration has been stymied. Americans who identify with the Tea Party overwhelmingly believe that immigrants represent an economic and cultural threat to the U.S. As Parker observes, the House GOP’s constituents “are anxious, even fearful that immigrants will take over the country.”