The Senate's rejection of the immigration bill was a shocker. On Tuesday, 64 senators, four more than the required 60, voted for cloture, that is, to consider the bill and a couple of dozen amendments. On Thursday, only 46 senators, 14 fewer than required, voted for cloture; 53 voted against, which was a vote to kill the bill. The bill's opponents had been assuming that if cloture had been voted, there would have been the 50 senators needed to approve the bill (only 50 because Democrat Tim Johnson of South Dakota has been ill and absent for all votes). The Thursday vote casts that into doubt. In May 2006, more than 60 senators voted for a bill that was more generous in its legalization provisions than the bill before the Senate last week. In June 2007, it appears, a Senate with more Democrats and fewer Republicans may not have had 50 votes for a more stringent bill.

Those of us who have favored a "comprehensive" immigration bill, with legalization and perhaps guest worker provisions as well as tougher border security and employer sanction provisions, obviously have some rethinking to do. We can rant and rave about the supposed ranting and raving on talk radio against the bill, but that won't get us anywhere. My own view has been that we need to regularize the flow of immigrants to make it work in tandem with the labor market, so as to minimize the number of people in the United States illegally and to improve our security at a time when foreign terrorists are seeking to wreak havoc on us. And as a practical matter, we have to provide something in the way of legalization of the 12 million or so illegal immigrants in this country. So what do we do now?

We have to start by recognizing why the voting public was strongly against the bill. "We have met the enemy, and he is us," the comic strip character Pogo said, and the enemy here is the us that have not enforced the law -- the executive and legislative branches, which have let the promise of the 1986 immigration law to become a dead letter and the voters who have not punished elected officials for doing so. The 1986 law purported to penalize employers who hired illegal immigrants. But because of the ease of obtaining forged identification documents, that has long been a dead letter. The 1986 law envisioned strict border security. But for too long the border remained a sieve.

As pollster Scott Rasmussen has shown, the opposition to the bill was fueled less by anger at "amnesty," the idea that illegals would be rewarded for breaking the law, than it was by an astringent skepticism that it would provide real border security. Americans may be willing to forgive those who were, by the actions of government and the inactions of voters, effectively invited to violate the law. But they don't seem to be willing to trust a government to enforce the law when it hasn't seemed to.

Here the Bush administration has a case to make. Border enforcement has dramatically improved. The catch and release program of OTMs (other than Mexicans) was ended last summer, a month ahead of schedule. Substantial miles of the border fence, voted by Congress last September, are being built. Technology provides us with means to seal the border in thinly populated areas in ways impossible in the 1980s and 1990s. Rhetoric aimed at showing a willingness to accept immigrants has concealed these achievements. Rhetoric emphasizing the increasing toughness and shrewdness at protecting the borders could create another impression.

Technology also could enable us to enforce employer sanctions better than we could in the 1980s and 1990s. When the 1986 law was passed, there was a strong consensus against anything like a national identity card. Now technology enables us to create a biometric identity card checkable against databases and difficult to forge. Mexico has a voter identity card that has worked quite well. The Real ID bill passed by the last Congress moves us in that direction. And the threat of terrorism has made us less afraid of a national identity card and more willing to recognize that if we want to keep track of immigrants and potential terrorists, we will have to let the government have the means to keep track of the rest of us as well.

There's not much hope that Congress will pass a big immigration bill this year or next. But the administration, by charging ahead on border security and setting the stage for a national identity card, can move the public toward accepting a comprehensive immigration bill in the years ahead.