It’s a widely accepted idea that Republicans are sitting on a demographic time bomb: The GOP is getting whiter and whiter in terms of the voters it attracts even as the country is growing increasingly diverse.

Marisa Abrajano, an associate professor of political science at the University of California at San Diego, doesn’t dispute that basic notion in a new study of the electorate. But she does suggest that the time bomb may well have a very long fuse — and that in the time before it explodes, Republicans could actually benefit electorally from a consolidation of the white vote.

“Given that whites still make up about three-quarters of the voters in the nation and will likely be the clear majority for decades to come, there is every reason to believe that whites will have a real say in who governs,” writes Abrajano in “Will Immigration Spark a White Backlash in America?” “Indeed the white population’s growing allegiance to the Republican Party points to a very different short term future — one that might more likely be highlighted by Republican victory than by Democratic dominance.”

As the title of Abrajano’s study suggests, she ties these demographic shifts closely to the ongoing debate over immigration — and, specifically, what to do about undocumented immigrants — and the effects on our politics.

That’s a particularly relevant conversation at the moment, given the crisis of undocumented children flooding the country’s southern border and the recently concluded debate over how much federal money to devote to solving that problem.

Republicans in Congress — particularly the House — have been resistant to passing any sort of broad-scale immigration reform legislation or, of late, dedicating the billions of dollars sought by President Obama to address the problems at the border.

That resistance — which conservatives in the House insist is based on a desire to see the border secured before the topic of what to do with the 11 million people here illegally can be debated — has led to significant handwringing among the party’s strategist class, which worries that the Republicans’ policies make them look unwelcoming to Hispanics.

Those fears were at least partly realized in the 2012 election. Mitt Romney won just 27 percent of the Hispanic vote, down from John McCain’s 31 percent in 2008 and far from the 40 percent that George W. Bush won in 2004. Just one in every 10 people who voted for Romney was not white; more than four in 10 Obama voters were non-white.

Those numbers were particularly frightening for Republicans because the white vote comprised just 72 percent of the overall electorate in 2012 — the lowest mark in modern presidential history.

Abrajano suggests that a much more overlooked number from the 2012 election might be more telling in terms of how immigration — and the policies the two parties propose to address it — will affect elections in the near term. That number is 20 — the percentage-point margin by which Romney beat Obama among white voters.

That was the second-largest margin among white voters for a Republican presidential nominee in three decades. (Only Ronald Reagan in 1984 won the white vote by a larger margin, and the Gipper did that in an election in which he was carrying 49 states against Walter Mondale.)

“In 1980 white Democrats dominated white Republicans numerically,” Abrajano argues. “As immigration’s impact on America has grown, whites have fled to the Republican party in ever larger numbers. The end result is that the principal partisan choice of white America has been totally reversed.”

In essence, she argues, the prominence of immigrants and immigration issues as well as the two parties’ varying responses to those issues have made it increasingly likely that the white vote will continue to consolidate behind Republican candidates in the near to mid-term.

The past two elections suggest that Abrajano may be on to something. Not only did Romney hit a near-historic high in the white vote in 2012, but Republicans won the white vote in the 2010 midterms by 23 points — a massive margin considering that whites comprised 77 percent of the overall electorate.

The coming 2014 midterms will put Abrajano’s theory to the test again. Over the past two years, House Republicans have failed to act on a comprehensive immigration reform package passed by the Senate and, most recently, have engaged in an extended contretemps about how much money to allocate to the border crisis. The lines between the two parties have grown even starker on immigration. Under Abrajano’s hypothesis, this should drive the white vote even more heavily for Republicans in 2014 as the party is increasingly seen as the home for those concerned about immigration and its effects on society.

What neither Abrajano nor almost any other right-minded political scientist or analyst is arguing is that over the long term the whitening of the Republican Party is a good thing, electorally speaking, for the GOP. Instead, Abrajano is suggesting that with Hispanics still voting in dramatically lower numbers than their share of the population, Republicans’ increasing reliance on white voters may not equal electoral doom. At least not yet.