As President Bush acknowledged in his meeting with the leaders of Canada and Mexico last week, immigration reform is going nowhere in Congress – and that’s too bad.

Bush told Mexican President Vicente Fox he would continue to promote his plan, but he couldn’t guarantee success.

Immigration reform is causing a deep split among Republicans. One side says: Tighten up the border and enforce the law. The other says: The law is grossly out of sync with reality and must be changed. Count me in the latter camp.

One of the leading advocates for the get-tough side is Rep. Tom Tancredo, a Colorado Republican. Tancredo recently bashed Bush’s proposal, which would set up a guest-worker program and give temporary permits to illegal immigrants already here.

“The proposal is wrongheaded,” Tancredo wrote. “It offers amnesty to 12 million to 15 million illegal aliens in our country, about 75 percent of them Mexican. This won’t solve our illegal alien crisis. In fact, it will only encourage more people to cross our borders illegally to wait for the next amnesty.”

Bush’s plan, writes Tancredo, “benefits only Mexico, not the United States.”

Hardly. The Pew Hispanic Center recently estimated the number of illegal immigrants in the United States at 10.3 million, a 23 percent increase over the last four years. Tancredo forgets that hiring is a voluntary transaction in which both parties benefit. Immigrants wouldn’t be here if the goods and services they produce didn’t offer real value for the U.S. economy.

Those who say immigrants take jobs only from Americans must explain why the jobless rate has been falling despite the influx of all those workers.

Immigrants take jobs that many Americans won’t. Immigrants are essential in many industries, including hospitality, construction, agriculture, food processing and health care. Imagine the economic shock if all that human capital was rounded up and thrown out of the country. And don’t forget, even illegal migrants pay sales taxes and many pay Social Security – while drawing no benefits.

As Tamar Jacoby notes in The Weekly Standard, the best analogy for the get-tough approach is Prohibition. Just as it was impossible to stop Americans from imbibing merely by passing a law, it’s equally futile to stem the inflow of illegal migrants solely through enforcement.

Certainly, more vigorous enforcement must be part of any reform, and Bush hasn’t done enough in that regard. But real reform also means finding ways to manage legally the entry of people who will come here anyway, given the historically steady demand for immigrant labor.

The failed get-tough approach, combined with the current toleration of a growing black-market labor pool, will only encourage the growth of enclaves where immigrants can live beyond the reach of authorities – with troubling implications for national security.

Bush would allow those already here illegally to work their way to legal status without allowing them to jump the line ahead of those applying via normal procedures. Critics like Tancredo call this amnesty, but Jacoby suggests a process more like probation, including the payment of fines.

Putting more illegal immigrants “on the books” would increase national security. Authorities would have a clearer idea who had entered the country and where they live. Names could be checked against lists of known terrorists. Immigration agents and Border Patrol officers could focus more resources on keeping terrorists out.

Until immigration quotas are adjusted so they’re commensurate with the demand from employers, migrants desperate to improve their lives and provide for their families will flow in – legal or not.

The policy choice is not whether to deport all the illegal immigrants. That’s not going to happen. The choice is whether we want them in the shadows or within the law.