The immigration crucible begins this week in the Senate, where conservatives opposed to legalizing undocumented immigrants will begin a summer siege.

The legislation will both expose and challenge the core pathology of the Republican Party -- that recurring tic by which the least constructive faction on any particular issue calls the ideological tune. (A budget compromise to put the nation's fiscal policy on track? Nah. Let's hold the global economy hostage over the debt ceiling instead. Negotiate improvements to Obamacare? No way: Better to cast toy repeal votes by the dozens.)

Immigration is different from other issues in a powerful way.

After five decades of using race as a political wedge to win elections, a process that transferred Dixie from Democratic to Republican control, Republicans can draw upon little goodwill from racial minorities. The party's undisguised efforts to destroy the first black president will cement black allegiance to the Democratic Party for decades to come. Of course, Republicans kissed off black voters (13 percent of all voters in 2012) decades ago and still won elections. The question is whether the party can similarly dismiss the rapidly growing Hispanic vote (10 percent) and Asian vote (3 percent).

The only answer is no.

An America's Voice/Latino Decisions poll released last week found that two-thirds of registered Hispanic voters personally know an undocumented immigrant and that a slightly higher percentage rate immigration reform "extremely" or "very" important. On immigration, Hispanic voters give Congressional Democrats a 65 percent to 25 percent favorable/unfavorable rating. The comparable Republican numbers are 26 percent to 59 percent -- even though Republican Senator Marco Rubio of Florida has been the public face of reform. In predicting their vote for Congress in 2014, poll respondents said they expected to support a Democrat over a Republican by 66 percent to 20 percent.

Some Hispanic voters have already concluded that the Republican Party is their foe. A 2010 poll found that almost one-third of Hispanics considered racism a factor in the immigration debate. And that was before anti-immigrant rhetoric reached its peak in the 2012 Republican presidential primary.

If fundamental mistrust of Republicans spreads to more Hispanics and Asians, demography will effectively ruin the Republicans as a presidential party -- and fast. "As the electorate overall diversifies, the Republican Party is not going to be able to win another national presidential election if they are not in the high 30s or 40s" among Hispanic voters, Latino Decisions pollster Matt Barreto told Garance Franke-Ruta in the Atlantic. (The 2012 Republican candidate, Mitt Romney, received about 27 percent of the Hispanic vote.) If the party proves incapable of producing a winning national coalition, the implications for Republican candidate recruitment, fundraising and other political mechanics become dire.

The Senate seems primed to pass bipartisan immigration legislation. And ABC News reported that House Speaker John Boehner "said he believes that passing an immigration bill in the House is the most important thing on his agenda this year."

Yet it's impossible to know how effectively Boehner can manage his unruly troops -- or how far to the right his definition of "immigration bill" will ultimately be. Last week, House Republicans voted to overturn President Barack Obama's executive order enabling young undocumented immigrants -- who had been brought to the U.S. as children -- to avoid deportation. As policy, the vote was pointlessly cruel. As politics, it was disastrous, targeting the most sympathetic group of undocumented immigrants for punishment, and revealing a Republican rank and file marching behind their most virulently anti-immigrant colleagues.

Writing in U.S. News under the headline "A Finger in the Eye of Hispanic Voters," Robert Schlesinger asked the obvious question: "Does this party have a death wish?"

We'll soon learn the answer.

(Francis Wilkinson is a member of the Bloomberg View editorial board. Follow him on Twitter.)