Thanks to the miracle of the Internet, you can go to the White House Web site, as I did last week, and download a copy of President George W. Bush’s speech on reforming U.S. immigration policy.

It was a very good speech, brightly written and well delivered, full of thoughtful passages like this: “Como antiguo gobernador, se que aplicar la ley y hacer respetar la frontera es particularmente importante. …”

No, wait. That’s not right. I must have downloaded the wrong version of the speech. On the White House Web site, you see, most of the president’s remarks are offered in your choice of English or Spanish.

Say what you want about the Bush communications team, these guys do know their constituency.

Or do they? The immigration debate is the most confusing and confused item on the political agenda these days and, for Republicans, a deeply divisive one. Bush shows commendable pluck in wanting to wade into it. The only problem is that, at first glance, he seems to want to wade into it from both sides at once.

Immigration is one of the few policy areas, like primary and secondary education, that has long been an object of intense and genuine interest to Bush, who was, after all, a two term governor of a border state with a large immigrant population.

In fact, illegal immigration was one of the issues on which candidate Bush staked his claim as a compassionate conservative in the 2000 election. “Family values do not stop at the Rio Grande,” Bush said in his standard stump speech then, hoping to draw a contrast with traditional conservatives whose attitude toward immigration, legal or otherwise, seemed more punitive than welcoming.

The generous tone of Bush’s “family values” line is reflected in the immigration reform that he first presented last year and reaffirmed last week.

The reasoning is clever if slightly paradoxical: The way to reduce the number of illegal immigrants is to make more immigrants legal. Unfortunately, paradox, like wit and irony, don’t play well in contemporary politics.

“Bush is saying something that can be hard to explain,” says Tamar Jacoby, an immigration specialist at the New York-based Manhattan Institute, which does research on economic policy. “He’s saying the way to control immigration and rationalize the system isn’t to crack down harder but to open up the channels for more immigrants.”

The details of Bush’s reform are deliberately sketchy; any comprehensive program with a chance of passing would have to be forged in Congress anyway.

In rough outline, Bush’s proposed “guest worker” program would bring immigrants under the umbrella of the law by increasing the number of them allowed into the country, registering them, matching them with employers for a fixed period of several years, and then offering them a shot at U.S. citizenship – after they’ve returned to their native country.

Bush’s approach reflects an admirable realism. For better or worse, entire U.S. industries, from agriculture to food processing to hospitality services, now rely on a flow of cheap, unskilled labor to take jobs that, as Bush put it last week, “Americans will not do.”

Restricting that flow of willing workers would cause an economic calamity that no federal official will seriously contemplate. Nor would anyone in a position of responsibility pretend it’s plausible to round up the 11 million illegal immigrants who are already in the U.S., ship them back to their homelands and then seal the border against their otherwise inevitable return.

Even so, many politicians, almost all of them Republicans, are willing to pretend that shutting off the flow of immigrants is a realistic option. And they think such a position offers their party a political advantage.

They’re almost certainly wrong – not only about the policy but also about the politics.

Polls do show that a steady majority of Americans favor restricting immigration. Yet the intensity of opinion about the issue – what pollsters call salience – is low. In a bipartisan poll last April, conducted for the National Immigration Forum by Democrat Celinda Lake and Republican Ed Goeas, respondents were asked to select from a list of 10 issues the one that worried them most. Only 5 percent chose immigration.

The loss last month by Republican gubernatorial candidate Jerry Kilgore in the heavily Republican state of Virginia underscores the issue’s dicey politics. Hoping to rouse his party’s rank and file, Kilgore made immigration crackdown a priority of his platform – and then, to his great surprise, lost the Republican exurban counties where illegal immigration is greatest.

“There’s always this sense among Republicans that ‘sealing the border’ will be a winner,” Jacoby says. “But it never works. There’s probably about 15 percent of the Republican base that are adamant about the issue and will vote on it.”

Bush’s concession to that 15 percent last week was to frontload his speech with tough talk. He boasted of the 60 percent increase in border-security funding his administration has overseen, the 3,000 new border guards it has hired and the 4.5 million illegal immigrants it has sent home.

“We are going to protect the border,” Bush said.

The tough talk may appear paradoxical. But it’s also part of Bush’s realism, and it shouldn’t obscure the heart of what he hopes to do: guarantee that the U.S., in its third century, remains the nation of immigrants that it was in its first two.

Mr. Ferguson is a columnist for Bloomberg News.