Get ready for some strident debate next month. Congress is preparing to tackle immigration reform.

Meeting President Bush's challenge to do so "without animosity and without amnesty" will require policymakers to settle four critical questions: 1) Does the White House's current approach resemble amnesty? 2) What will it cost taxpayers to allow illegal immigrants and their relatives to become citizens? 3) How will reform affect national security? 4) What will a Democrat-controlled House and Senate present to President Bush?

Before they begin debating, lawmakers should consider some recent political history.

In the Reagan years, a Democrat-controlled congress passed the Immigration Reform and Control Act of 1986. This amnesty legalized 2.7 million illegal aliens.  Eligible aliens had to pay a fee, learn English, understand American civics and prove that they hadn't been convicted of a serious crime or a series of minor crimes. They were then promised citizenship after five years of continuous residence in the U.S.

Last year, the Senate passed a bill that would have granted a similar pathway to citizenship for an estimated 10 million illegal aliens (there are an estimated 12 million currently here) after an 11-year period. The bill would have allowed " chain migration," i.e., individuals could bring spouses, children, brothers, sisters and parents.

Robert Rector of The Heritage Foundation projected that this approach would greatly expand legal immigration from the estimated 950,000 per year today to a staggering 66 million over the next 20 years. If the 2007 approach resembles the approach of Sens. Ted Kennedy (D-Mass.), John McCain (R-Ariz.), Chuck Hagel (R-Neb.), and Mel Martinez (R-Fla.) in the last Congress, then the new proposal will be a larger version of the 1986 amnesty. The cost to taxpayers would be overwhelming.

President Bush called for a balanced budget by 2012 in his State of the Union. That's unlikely to happen if lawmakers add new programs to aid low-wage and no-wage citizens.

Many states would have to pay for education and other local services for the new members of our society if this proposal becomes law. Taxpayers will need to watch this debate closely to make sure that they aren't stuck paying higher taxes to shoulder the burden of adding all these new citizens to our generous welfare system.

And let's not forget security concerns. Remember, the 9/11 terrorists abused our immigration laws by overstaying visas. Today, it's important to secure our southern border so potential terrorists can't simply walk across from Mexico. We also should use biometric technologies to track guests here on one of the many different visa categories. National security can't be overlooked as we craft a new immigration policy.

Last year's Senate bill will be a starting point for negotiations in a Democrat-controlled Congress. Democrats will need the support of at least nine Republicans in the Senate to defeat a potential filibuster by conservative Republicans lead by Sen. Jeff Sessions (R-Ala.).

Last time, the bill passed the Republican-controlled Senate 62-36, although a majority of Republicans opposed it. If the new Senate votes to grant a more expedited pathway to citizenship or grant amnesty to a larger class of illegal aliens, it may be difficult to overcome the potential opposition of members, both Republicans and Democrats, who fear voting in favor of a more expansive pathway to citizenship.

Congress should take a more conservative approach, in the form of a guest-worker program with no amnesty and no automatic pathway to citizenship.

It's possible to support a temporary and market-based approach that wins the support of the American people and the business community (which wants access to more low-skilled workers).

In the last Congress, Sen. Kay Bailey Hutchison (R-Texas) promoted the SAFE Visa program, which would have allowed a visa holder to come in for 10 months, then leave for 2 months without the promise of citizenship. This is an excellent model for a true temporary worker program. It must respect the rule of law and should not grant any form of amnesty, and that includes granting automatic citizenship to the children of illegal aliens born here.

An effective guest-worker program will be difficult to draft. But lawmakers owe it to all Americans to write a law that will secure our borders and be truly temporary.

Brian Darling is director of U.S. Senate relations at The Heritage Foundation, a leading Washington-based public policy institution.