This one chart shows you the politics of U.S. citizenship

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Donald Trump has reignited the immigration debate in the United States. One of his main immigration reform proposals is to end birthright citizenship, that is, to deny citizenship to children born in the U.S. to undocumented parents. He struck a nerve. Birthright citizenship divides Americans along clear partisan, ideological, and demographic lines. But while this is one of the more radical elements of Trump’s broader immigration reform proposals, the issue of birthright citizenship is not new.
In the House, resolutions and bills have been introduced on the issue in every Congress since 1993: House Resolution 129 (1993-1994), House Resolution 93 (1995-1996), the Citizenship Reform Act (1997-2000), H.R. 190 (2001-2002), the Citizenship Reform Act again (2003-2006), and now the Birthright Citizenship Act (2007-present).
The furthest this issue has gone in Congress was back in December 1995, when joint hearings were held in the House Judiciary Committee. The Fourteenth Amendment states, “All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States.” Legislative efforts to deny birthright citizenship try to exclude undocumented immigrants from the meaning of “subject to the jurisdiction thereof.”
At the time, testifying on behalf of the Department of Justice, Assistant Attorney General Walter Dellinger under President Bill Clinton said unequivocally, “A bill that would deny citizenship to children born in the United States to certain classes of alien parents is unconstitutional on its face.” In her testimony, former Texas congresswoman and Democrat Barbara Jordan, then chair of the Commission on Immigration Reform, added forcefully that denying birthright citizenship “will divide the country on the most profound level—the question of who we are as a people and who says so.”
While no legislation denying birthright citizenship has made it to the floor of the House for a vote, analyzing who sponsored and co-sponsored these bills reveals which representatives from which parties and districts have tried to change birthright citizenship.
What kind of legislator signs on to change birthright citizenship?
Who in Congress supports denying American citizenship to children who are born in the U.S. to undocumented parents? Between 1993 and 2015, 247 representatives in the House sponsored or co-sponsored legislative efforts to deny birthright citizenship. These efforts have been highly partisan. Out of these 247 representatives, 96 percent were Republican.
But the Republican Party is hardly uniform. The Republican legislators who have sponsored or co-sponsored birthright citizenship legislation are significantly more ideologically conservative than their fellow GOP legislators.
Let’s look at this using one of the most widely used measures of left-right political ideology, the DW-Nominate score. The higher the score, the more ideologically conservative the representative. The median score for GOP representatives who have supported changes to birthright citizenship is 24 percent higher—that is, more conservative—than the median score for all other Republican representatives in the House. Figure 1 illustrates the ideological differences between legislators who have and have not sponsored or co-sponsored legislative efforts to deny birthright citizenship, for both Republicans and Democrats.

Who do these legislators represent?
Now let’s look at the districts that these legislators represent. When it comes to demographics, the average white percentage of the population is almost 10 percent higher in House districts whose representatives have supported efforts to deny birthright citizenship compared to other House districts. This difference, 73 percent compared to 64 percent, is statistically significant.
Let’s break this down even further. The Hispanic/Latino percentage of the population is 5 percent lower in House districts whose representatives have supported changes to birthright citizenship compared to other House districts. This difference, 11 percent versus 16 percent, is also highly statistically significant.
To put this into perspective, representatives who have sponsored or co-sponsored birthright citizenship legislation represent districts whose demographic composition more closely resembles what the country looked like in 1990 than it does today, a quarter of a century later. These demographic differences have been emblematic of the birthright citizenship debate across a dozen Congresses and three presidencies.
Could these legislators repeal birthright citizenship?
What if a floor vote were held today on changing birthright citizenship? If we extrapolate from the kinds of legislators who have, in the past, sponsored and co-sponsored birthright citizenship legislation, we can simulate a floor vote in the House. This shows that only 74 representatives would likely vote yes to deny birthright citizenship and 29 would be on the fence. A most likely scenario would still leave proponents of denying birthright citizenship 115 votes short of passage.
Of course, there is noise in using sponsorships and co-sponsorships to forecast floor votes. But two decades of failed attempts in the House suggest that if birthright citizenship were put to a floor vote, it would fail.
But in this presidential election cycle, the issue of birthright citizenship is more about politics than policy. It may be that GOP presidential candidates who take hard lines on birthright citizenship are trying to win over conservative GOP primary voters. But as the 2012 presidential campaign showed, pivoting from taking a hard line during the primary to taking more moderate positions during the general is becoming increasingly difficult, particularly on immigration. Remember, Mitt Romney is widely viewed as having lost the Hispanic/Latino vote in part because of his “self-deportation” remarks during a presidential primary debate.
An increasingly dense network of ethnic media, particularly Spanish-language media, for whom immigration is a major focus, will be unlikely to let inflammatory statements be forgotten. The GOP did itself no favors when Trump kicked Univision anchor Jorge Ramos out of a recent press conference, which promptly led “Jorge Ramos” to begin trending on Twitter. Jorge Ramos has been an anchor at Univision for nearly 30 years and often draws larger U.S. television audiences than ABC, CBS, NBC, and FOX.
Seventy-one percent of Hispanics/Latinos and 73 percent of Asians voted for President Obama in 2012. Of course, we have to wait until the electoral college dust settles before we know how threats to birthright citizenship and positions on immigration generally affected the 2016 cycle.
But here’s what we do know. Policymakers who have sponsored or co-sponsored legislative efforts to deny birthright citizenship represent districts that, demographically, resemble a bygone America—this version of America may very well be what GOP presidential candidates are appealing to.
But the Electoral College has changed along with the country. The path to 270 is now exceedingly difficult without the support of a demographically broad swath of America’s increasingly diverse electorate.
Tom K. Wong is assistant professor of political science at UC San Diego. He is the author of a forthcoming book about U.S. immigration politics and of the recently released book, “Rights, Deportation, and Detention in the Age of Immigration Control.”