Dog whistle politics have served Republicans well. But with shifting demographics, they may become an albatross around the party’s neck. No issue reflects that dynamic as clearly as immigration reform. Failure to address a broken system has alienated key constituencies since George W. Bush’s abortive attempt to pass the McCain-Kennedy bill back in 2005.

And it continues to do so today.

In January, Republican leaders in the House unveiled a long-anticipated set of principles for immigration reform, finely tailored to gain the support of a skeptical GOP caucus.

They require a major increase in both border security and interior immigration enforcement before any undocumented families could come out of the shadows. They offer a form of legalization, but not the much debated “path to citizenship.” Rather, unauthorized immigrants would eventually be able to apply for work permits if, as presented in the Republican outline, “they were willing to admit their culpability, pass rigorous background checks, pay significant fines and back taxes, develop proficiency in English and American civics, and be able to support themselves and their families (without access to public benefits).”

Despite the conservative tilt, as of Wednesday, Roll Call reports that only 19 House Republicans have openly expressed support for their leadership’s initiative, and only two others have even entertained the possibility. That, in a nutshell, reflects the greatest challenge of a party that faces strong headwinds in national contests going forward.

The party is between a rock and a hard place. Thousands of words have been written about the potential consequences that may follow if the GOP further alienates America’s fastest growing voting blocs. National campaign strategists worry that in a few election cycles, Republicans could be reduced to a rump Southern party.

But those worries aren’t necessarily embraced by the rank-and-file. A combination of fierce gerrymandering, natural migration patterns and ideological polarization have resulted in a huge number of Republicans representing districts that are increasingly homogenous, both ideologically and ethnically. House Republicans won’t pass immigration reform, even though their party must, because many of them have little incentive to do so.

As Nate Silver pointed out in The New York Times, between 1992 and 2012, the number of competitive “swing” districts in the United States dropped from 103 to 35. Meanwhile, “the number of landslide districts — those in which the presidential vote margin deviated by at least 20 percentage points from the national result — has roughly doubled. In 1992, there were 123 such districts (65 of them strongly Democratic and 58 strongly Republican). Today, there are 242 of them (of these, 117 favor Democrats and 125 Republicans).”

Lawmakers’ voting patterns have followed this trend. According to National Journal’s congressional rankings, over the past four years, no Senate Democrat has had a more conservative record than the most liberal Republican, and vice versa. In the House, there were only four members whose voting records fell within that overlapping center last year. That represents an enormous shift since 1982, when “58 senators and 344 House members had voting records that put them between the most liberal Republican and the most conservative Democrat.”

Racial polarization has also increased in House districts. Pollster Charlie Cook notes that between 2000 and 2010, the non-Hispanic white population fell from 69 to 64 percent, but after redistricting in 2010, the average white share of Republican districts actually increased from 73 to 75 percent. Even that doesn’t tell the whole story; an analysis by National Journal’s Scott Bland found that 111 of the 233 House Republicans represent districts that are more than 80 percent white.

Those lawmakers may worry about the party’s national standing, but their first concern is getting re-elected every two years in these increasingly uniform districts. They fear primary challenges from the right. And while liberals often tout polls showing Republican voters’ support for immigration reform, there’s an “intensity-gap” among the party faithful — those opposed to reform are often the loudest voices in the room. And, as Benjy Sarlin noted for the website Talking Points Memo, many Republican voters who support immigration reform hold negative views of immigrants themselves. They tend to see them as a burden on society.

It’s a big problem for the party when Republicans express that view in public. Although relatively small in number, Asian-Americans are the fastest growing demographic and only 26 percent of them supported Mitt Romney in the 2012 election. Behind them are Latinos, 27 percent of whom backed Romney. Both groups skew younger than the population as a whole, meaning that with each election cycle more come of voting age. And both have soured on the GOP since George Bush won around 40 percent of their votes in 2004. Their loyalties aren’t determined by immigration policy alone, but the Republican Party’s perceived hostility to minorities threatens to turn each into a reliably Democratic voting bloc.

It’s unfair to paint an entire party as a bunch of nativists, but despite the growing demographic threat, dog whistles still sound in Republican politics. Texas gubernatorial candidate Greg Abbott calls South Texas a “Third World country,” infamous xenophobe and former congressman Tom Tancredo is favored to win the GOP nomination to run for governor of Colorado, Rep. Louie Gohmert (R-TX) has warned of immigrants bringing “terror babies” into the US and Rep. Steve King (R-IA) — a self-proclaimed contender for the 2016 presidential race — said last summer that for every child of an undocumented immigrant “who’s a valedictorian, there’s another 100 out there who weigh 130 pounds — and they’ve got calves the size of cantaloupes because they’re hauling 75 pounds of marijuana across the desert.”

Add the voices of right-wing talk-radio and other conservative media, and one can see why national GOP strategists are losing sleep: they fear turning broad swaths of the country into California. It was long a swing state – until demographic shifts and Governor Pete Wilson’s 1994 campaign demonizing immigrants for the state’s problems. Before that, Republicans had won eight of nine presidential contests in the Golden State, and held the governorship in seven of 10 elections. Now California is reliably blue.

The backdrop to all of this is the coming of age of a wave of millennials, young people who appear to be one of the most progressive generations in America. Shaped by the War on Terror and the failures of Bush’s two terms, these are not going to be voters who come running to the high-pitched shriek of dog whistle politics. The youngest are 14 years old, and as they approach voting age, Republicans should be embracing the richness of America’s diverse population. Yet their most loyal constituents would never tolerate it.