WASHINGTON —  As Congress prepares for a showdown over immigration policy, President Bush urged lawmakers Thursday to have a "civil debate" that respects people of all backgrounds.

"Ours is a nation of law and ours is a nation of immigrants, and we believe that we can have rational, important immigration policy that's based upon law and reflects our deep desire to be a compassionate and decent nation," Bush said.

He urged a serious debate on the issues at a time when advocates on both sides have been playing to voters' gut emotions.

"When we discuss this debate, it must be done in a civil way," Bush said during a meeting with groups pushing for changes to immigration laws. "It must be done in a way that brings dignity to the process. It must be done in a way that doesn't pit people against another."

Bush wants Congress to create a worker program under which participants could gain legal status for a specific time and then be required to return home. It would not provide an automatic path to citizenship.

"Our government must enforce our borders," Bush said. "We've got plans in place to do so. But part of enforcing our borders is to have a guest worker program that encourages people to register their presence so that we know who they are and says to them, `If you are doing a job that Americans won't do, you're welcome here for a period of time to do that job.' "

The Senate Judiciary Committee is considering a bill with a guest worker program. If that measure does not move forward, Senate Majority Leader Bill Frist planned to push debate on his bill. Frist's bill sidesteps the question of temporary work permits and would tighten borders, punish employers who hire illegal immigrants and provide more visas.

Senate Minority Leader Harry Reid, D-Nev. has threatened to do everything in his power, including filibuster, to thwart the legislation.