President Bush promoted his administration's efforts to get a grip on illegal immigration, spotlighting a plan to tighten security along the southern border and calling for a guest-worker program that would allow about 11 million illegal immigrants to work legally in the country temporarily before forcing them to return home.

Speaking Monday at an Air Force base here about one hour north of the Mexican border, Bush put his rhetorical emphasis on measures sought by many Republicans fearful of swelling illegal immigration: stronger border enforcement with high-tech detection systems, larger centers to detain those captured, swifter proceedings to deport them and increased policing of illegal immigrants in the interior.

"Those who enter the country illegally violate the law," Bush said. "The American people should not have to choose between being a welcoming society and a lawful society. We can have both at the same time."

But the president faces an uphill battle in the House and Senate to realize his vision of reform, which is drawing intense skepticism from many allies in his own party who believe his approach is not tough enough. In the coming weeks, the White House must persuade lawmakers to forge several immigration bills, differing widely in scope, into a single policy.

Bush's call for Congress to enact a temporary-worker program is especially contentious within the GOP. The president's proposal would allow foreign workers to enter the country for a fixed period -- most likely three years -- to fill jobs that go unwanted by Americans, but some Republicans reject that as too close to amnesty for illegal immigrants. The workers would be given a "tamperproof" identification card, and would be required to leave the country once their term in the country expires.

"Listen, there's a lot of opinions on this proposal -- I understand that," Bush said. He added that the workers would not be put on a path to citizenship and that workers who entered the country illegally would have to pay a penalty before entering the program.

"I oppose amnesty," Bush said.

Will Adams, a spokesman for Rep. Tom Tancredo (R-Colo.), said his boss was not convinced. He called the president "Clintonesque," for advocating amnesty without actually calling it that. "It's new lipstick on an old pig," Adams complained. He said a guest-worker program would reward immigrants who entered the country illegally.

House Judiciary Committee Chairman F. James Sensenbrenner Jr. (R-Wis.) is writing legislation that does not include a guest-worker program, Adams said. The committee's spokesman, Jeff Lungren, could not be reached to comment after the president's speech.

Others called Tancredo out of step with a party and president who are trying to tread a middle path on immigration -- enforcing the law while projecting a more welcoming tone and recognizing the reality of an economy in which newcomers play an essential role. Tancredo, for instance, has angered some Republicans by proposing to deny U.S. citizenship to children born to illegal immigrants, a constitutional right.

"It would be unprecedented to take such a thing to the floor," said Cecilia Munoz, an analyst for the National Council of La Raza, a Latino civil rights group. "It would be an outrage that my community would remember."

Bush has worked aggressively to increase the GOP's share of the historically Democratic vote of Hispanic Americans. Many business leaders, meanwhile, support a guest-worker plan.

But the president in his speech made plain that he is sympathetic to people, particularly in border states such as Arizona and New Mexico, who view illegal immigration largely as a social and economic burden and want a get-tough approach. His emphasis on border security marked a rhetorical shift. Previously, Bush spent more time touting a guest-worker program that would ease the way for undocumented immigrants to stay in the United States.

Democrats also are divided on the issue, as the Democratic governors of New Mexico and Arizona have declared states of emergency because of the influx of illegal immigrants. Bush's decision to emphasize border security disappointed some immigration advocates, who said that the nation's huge investments in new Border Patrol agents, electronic sensors, infrared imaging devices and border barricades have not stemmed the problem.

"Over the past decade our nation has taken unprecedented steps to secure the border," said Bishop Gerald Barnes, chairman of the U.S. Conference of Catholic Bishops' Committee on Migration.

"But the number of undocumented has more than doubled, and the number of deaths in the desert has risen dramatically. Clearly, a more comprehensive approach which emphasizes legal status for migrants and legal channels for migration is needed."

Many legislative leaders say they agree that a comprehensive approach is needed, but which one is a matter of competition. A bill written by Sens. John McCain (R-Ariz.) and Edward M. Kennedy (D-Mass.) and another by Sens. Jon Kyl (R-Ariz.) and John Cornyn (R-Tex.) offer guest-worker programs, but the first bill allows illegal immigrants already in the country to stay and work if they pay a hefty fine, and the other would force them to leave in five years and come back to participate in any program. Senate Majority Leader Bill Frist (R-Tenn.) said the chamber will attack the issue early in the new year.

Whatever the outcome, said Tamar Jacoby, a conservative Manhattan Institute expert on immigration, it was time for the president to take the lead.

"He has offered a very detailed plan for intensified enforcement on the border and in the interior," she said. "That should meet voter concerns about immigration getting out of control. This is the president finally using the bully pulpit and his political capital."

Fears reported from Washington.

President Bush arrives for a speech at Davis-Monthan Air Force Base in Tucson.