Far too many cracks in homeland security since September 11 can be traced directly to Congress. Trying to show they are really serious about security, Washington lawmakers have wound up piling more missions and responsibilities on the Department of Homeland Security than the crisis-born agency could accomplish.

The immigration-reform bill now under consideration would only make the problem worse. In granting amnesty to millions of illegal immigrants, the Senate proposal would further overwhelm DHS's capacity to manage immigration services, enforce the law, and ramp up border security.

Giving more missions to DHS now is a recipe for failure. Rather, Congress and the administration should free homeland-security officials to focus on current missions, where their existing authority can build a powerful deterrent to illegal migration.

Remember, DHS has yet to complete many long-standing security initiatives. Here are just five:

• Meet passport requirements. The Western Hemisphere Travel Initiative of 2004 requires U.S. and Canadian citizens to carry a passport or equivalent document when crossing our common border. What followed? A backlog of 500,000 passport applications. DHS and the State Department last week announced the delay of full implementation until January.

• Process legal migration. An ombudsman's report earlier this year found DHS' Citizenship and Immigration Services swims in a backlog of more than 1.3 million applications for legal immigration. Other reports put the number as high as 4 million.

• Implement the Secure Flight Initiative. Designed to screen manifests for domestic flights against the Terrorist Watch List, this system offers the kind of capability that could have stopped some of the September 11 terrorists. The administration intended this priority recommendation of the 9/11 Commission to be fully operative in 2005, but keeps granting extensions to DHS.

• Show travelers the exit. The U.S. VISIT system is supposed to screen foreigners as they enter and leave the country, but the government has failed to implement a mandatory exit process. No electronic means exists for verifying a traveler's identity -- think of this! -- and confirming he has boarded an outbound flight. (Congress, by the way, mandated this system years before the September 11 attacks.)

• Deport fugitive aliens. Many illegal aliens don't show up for court dates after they're caught and released pending a deportation hearing. Some 630,000 of these fugitive aliens continue to evade vastly outnumbered Immigration and Customs Enforcement authorities.

Given recent assurances, it's important to recall that gaining "operational control" of the border with Mexico was the stated goal of the Secure Fence Act of 2005. That's been on the books for quite some time. Yet even in optimistic estimates, DHS concedes it will need another 18 months to three years to carry out the mandated security requirements.

It's not clear whether that will happen before or after DHS conquers the daunting new challenges presented in the Senate's immigration legislation.

One challenge is to provide immigration services for the 12 million to 20 million unlawfully present persons who would be granted amnesty.

Another is to establish an electronic system of determining employment eligibility -- to verify that any given one of us is entitled to work legally in the United States. This system would have to be easily accessible to employers. It also would have to be capable of querying various databases containing information on more than 130 million employees and 7 million employers.

It is simply unrealistic to believe that DHS could accomplish these tasks quickly and efficiently. Yet the Senate bill requires that the agency complete them and additional border-security measures before the government could implement a temporary worker program.

Such delay, of course, would allow illegal immigration to increase while providing more opportunity for opponents to undermine the temporary worker program.

It makes far more sense for the Administration to concentrate on using DHS's existing authority to make real security progress. For starters, it can:

• Increase the number of Border Patrol agents. The Administration should fulfill its goal of hiring 3,000 agents per year -- more than five times previous annual totals. Private contractors can perform duties such as patrol and detention and removal of illegals.

• Cooperate with state and local law enforcement. These efforts should focus on enhancing border security and confronting criminal aliens.

• Deploy border technology and obstacles. Unimplemented plans include sharing intelligence, expanding capabilities through the SBI Net program and building strategically placed fences and other obstacles.

• Target specific industries for enforcement. DHS knows where undocumented workers are most prevalent, and which businesses intentionally hire illegal workers to undercut competitors and reap illegal profits.

What can Congress do to help? First and foremost, refuse to grant amnesty to those who are in our country solely because they broke our laws. By rejecting amnesty, we as a nation will begin to discourage and deter future illegal immigrants.

Second, establish a temporary-worker program. We should provide legitimate opportunities for industries to find needed employees -- and for foreign nationals to visit the U.S. to work.

These measures will not remove everyone who is here unlawfully. Nor will they seal our borders. By taking these steps, though, our government can gain control of the southern border, get serious about workplace enforcement and stop tempting more illegal crossings.

It's a much better plan than handing DHS mission impossible -- and handing the rest of us more empty promises.

James Jay Carafano is senior research fellow for national security and homeland security in the Douglas and Sarah Allison Center for Foreign Policy Studies at the Heritage Foundation.