President Bush urged Congress to extend a deadline for illegal immigrants to remain in the United States while they pursue legal residency.

White House spokesman Ari Fleischer said the president was sending a letter to House and Senate leaders Tuesday expressing his support for extending the deadline to take advantage of a temporary regulation change that spared illegal immigrants from having to travel to their home countries before seeking a green card.

Typically, illegal immigrants who leave the United States are barred from returning for up to 10 years.

The original deadline passed at midnight Monday. Immigration offices around the country were flooded with last-minute requests.

Several bills are pending in Congress to address the problem, and Fleischer said Bush supports extending the deadline so that many immigrant families can remain intact. The White House estimated that an extension would affect about 200,000 people.

"The president is very concerned about what would happen to families of immigrants ... who would be forced to separate from their loved ones," Fleischer said. "The president stands on the side of these immigrants and their families."

Bush was sending letters to House Speaker Dennis Hastert, R-Ill., House Minority Leader Dick Gephardt, D-Mo., Senate Majority Leader Trent Lott, R-Miss., and Senate Minority Leader Tom Daschle, D-S.D. He plans to work with lawmakers to determine how long the extension should last, Fleischer said.

"He wants to sign legislation to protect these immigrants," Fleischer said.

The new law, which took effect in December, will assist approximately 640,000 illegal immigrants. To apply, an immigrant must be sponsored by an employer or by a close relative who is a U.S. citizen or legal permanent resident.