Washington ? President Bush challenged Congress on Thursday to pass a comprehensive immigration bill and said that he wasn’t afraid to take on his own Republican Party in the process.

“The American people expect us to meet our responsibility and deliver immigration reform that fixes the problems in the current system,” Bush said in a speech to the U.S. Chamber of Commerce. Business has been a key ally to Bush and those in Congress who agree with him that a broad approach is the solution to illegal immigration.

The Senate passed a sweeping bill before it left last week for the Memorial Day recess. It would provide a path to legalization for many of the estimated 12 million illegal immigrants living in the United States and also create a new guest-worker program. Participants in that program would also be allowed to eventually adjust their status.

But in December, the Republican-led House passed a bill that dealt solely with enforcement. The two sides would have to work out their differences to send something to Bush’s desk.

House Judiciary Committee Chairman James Sensenbrenner, R-Wis., scheduled to be the House’s lead negotiator on the bill, has labeled the Senate bill as amnesty and said he would not accept any such provision.

Without naming Sensenbrenner, Bush took aim at those holding that view during his speech.

“Some members of Congress argue that no one who came to this country illegally should be allowed to continue living and working in our country, and that any plan that allows them to stay equals amnesty, no matter how many conditions we impose,” Bush said.

Bush added that while he appreciates some lawmakers “deeply felt principles,” he believes their approach is ” wrong and unrealistic.”

Senate and House leaders have yet to name conferees, but could do so next week.

Bush embraced most of the Senate bill in his speech. But he departed from it in outlining his thoughts about a new guest-worker program.

Bush told the Chamber that the best way to stop the flow of illegal immigrants is “to make a temporary worker program a part of immigration reform.”

He described a program that “creates a legal path for foreign workers to enter this country in an orderly way for a limited period of time.”

Temporary workers, he said, “must return to their homes at the conclusion of their stay.” The Senate bill would allow guest workers to stay and earn a path to legalization.

Bush also made it clear to the business audience that he supports provisions in both the Senate and House bills to increase penalties for employers who hire illegal immigrants.