In his weekly Saturday radio address, Bush said the bill would not grant amnesty to illegal immigrants, that they would have to pay fines and take other steps to get on a path to legal status and possibly citizenship.
"Securing the border and upholding family values are not partisan concerns," the president said. "They must be addressed, and this bill is the best way to do it."
Bush recorded his address Friday in Germany where he was attending a summit with other world leaders.
The White House and a bipartisan group of senators drafted the wide-ranging bill, but they could not overcome steady attacks from the left and right during weeks of Senate wrangling. When the Senate failed Thursday to end debate and schedule a vote, Democratic leaders set the bill aside with no promise of reviving it.
Bush plans to lunch with Republican senators in the Capitol on Tuesday, part of a more hands-on approach to persuading party conservatives that the compromise bill is much better than the status quo.
In his radio address, Bush acknowledged mistakes in handling immigration and pledged to improve the bill as it moves through Congress.
"Today, illegal immigration is supported by criminal enterprises dedicated to document forgery, human trafficking, and labor exploitation," he said. "This is unacceptable, and we need to fix it in a way that honors our finest traditions."
He said the bill "puts border security first, establishes a temporary worker program to meet the legitimate needs of our growing economy, sets up a mandatory system for verifying employment eligibility, and resolves the status of the estimated 12 million people who are here illegally."
Conceding that a 1986 immigration overhaul largely failed, the president said his administration "is determined to learn from the mistakes of the past decades." The bill would double the number of Border Patrol agents, he said, build more border fences and employ infrared sensors and unmanned aircraft to detect illegal border-crossers.
"Unlike the 1986 law, this bill gives honest employers the tools they need to ensure that they are hiring legal workers," Bush said, including "a tamper-resistant identity card." Businesses that "knowingly hire illegal aliens will be punished," he said.
Addressing the word that has rallied the bill's opponents, the president said: "Amnesty is forgiveness with no penalty for people who have broken our laws to get here." The bill, he said, "requires illegal workers to pay a fine, register with the government, undergo background checks, pay their back taxes, and hold a steady job."
If those immigrants eventually want a green card for permanent residence, he said, they will have to pay another fine, learn English "and return to their home country so they can apply from there."