Along the U.S.-Mexico border, congressional candidates who advocated enforcement-only — but not comprehensive — immigration reform found support dropping by more than 21 percent in precincts with significant Latino constituents, costing them the election.

That was the finding in a recent report, titled “Border Wars: The Impact of Immigration on the Latino Vote,” by Richard Nadler of the conservative Americas Majority Foundation. The study involved 145 precincts and 175,000 voters.

The same report showed that Republican candidates supporting comprehensive immigration reform (some combination of guest-worker programs, earned legalization and security measures) lost only 4 percent of their support.

Nadler warns, “When a politician heads into the murky territory of mass deportations, or rejection of guest-worker programs, or criminalization of the civil infractions of undocumented work, the political penalty he pays among Latinos is harsh and prompt.”

This matters because the Republican Party may have begun defining itself, through its presidential candidates, as uninterested in cultivating Latinos for the party, further eroding any gains made since the 1970s. Add to that the Bush policy on Iraq and greater income disparity during his administration, and the scenario is set to alienate Latinos for a generation.

One more self-inflicted wound occurred last month at the Presidential Forums sponsored by Univision, the Spanish-language television network.

Calling it a “forum” (singular) better represents what actually happened. Only Arizona Sen. John McCain was willing to show up. The Republican event was canceled. The Democratic debate, meanwhile, with eight candidates, took place Sept. 9. It drew 4.6 million viewers, more than the average 4.3 million viewers of the English-language debates on ABC, CNN, Fox News Channel and MSNBC.

The same kind of snub shown Latinos visited Tavis Smiley, who moderated the All-American Presidential Forum on PBS. The Republican front-runners failed to attend the event, where questions would have come from journalists of color. The so-called “second tier” candidates did appear.

Lesley Sanchez, in her book “Los Republicanos: Why Hispanics and Republicans Need Each Other,” warns that an unwelcoming party and intolerance, as expressed on immigration issues, could wreck the party for Latinos. This is a voice to listen to. The fact is, the fulcrum has tilted and it is now the Republicans who need a Hispanic constituency to remain a national party. And immigration is their crucible.

Republicans have long struggled to form voter majorities in order to win elections. Among their most successful approaches were Richard Nixon’s “Southern Strategy” and “silent majority,” Ronald Reagan’s faith-based appeals and George W. Bush’s more generic “compassionate conservativism.”

Rarely, if ever, mentioned in this context was the 1972 presidential-election outreach that first put Latinos on the map as a Republican constituency. But in the years since, gains were made by addressing, not dodging, the very people they sought, and by accenting the positive.

Strangely, just when Latinos in the Republican Party (with Florida Sen. Mel Martinez as the GOP’s co-chair) should drive the agenda, there’s little sign of that. And the party might not have the capacity any longer to win. The presidential front-runners don’t seem to get it — how to connect people to policy, that if you want to add, don’t subtract.

Democrats, as it stands, could capture New Mexico, Nevada, Colorado, Florida, and Iowa in November 2008, according to Nadler. That means any edge Republicans might have had in a national election will have disappeared.

If Republican candidates don’t come up with some new, broad, comprehensive immigration policy, and unless they stop further alienating the people they need for a winning coalition, then you can kiss the party goodbye.

Like Titanic, the Republican Party could sink as a majority party for the foreseeable future. All that’s left will be Democratic officeholders — and high-dollar lobbyists, of course.

(Jose de la Isla, author of “The Rise of Hispanic Political Power” (Archer Books, 2003), writes a weekly commentary for Hispanic Link News Service. E-mail joseisla3(at)