"I'm sure you've heard some of the talk out there, people defining the bill. It's clear they haven't read the bill," Mr. Bush said. "They're speculating about what the bill says and they're trying to rile up people's emotions."
Mr. Bush appealed to skeptics of the plan to give it a chance, saying it will make the borders more secure and treat illegal immigrants with respect — but not amnesty.
"My answer to the skeptics is, 'Give us a chance to fix the problems in a comprehensive way that enforces our border and treats people with decency and respect. Give us a chance to fix this problem. Don't try to kill this bill before it gets moving,'" Mr. Bush said.
He attacked opponents of the plan, suggesting they "don't want to do what's right for America."
"The fundamental question is, will elected officials have the courage necessary to put a comprehensive immigration plan in place," Mr. Bush said against a backdrop of a huge American flag at the Federal Law Enforcement Training Center.
He described his proposal, which has been accepted by a bipartisan group of senators, as one that "makes it more likely we can enforce our border and at the same time uphold the great immigrant tradition of the United States of America."
Mr. Bush spoke at the nation's largest training center for law enforcement. He chose the get-tough setting as a counter to conservative critics' ferocious denunciation of a Senate proposal as being soft on people who break the law. Hoping to blunt that message, Mr. Bush emphasized that any new options for immigrants and foreign workers would not start until tougher security is in place.
The presidential stop came during a congressional recess, with senators back home and facing pressure from both left and right on the immigration plan. His aim is to build momentum for the legislation, perhaps his best chance for a signature victory in his second term. The Senate expects to resume debate on it next week.
Mr. Bush repeatedly cast the matter as one of political courage.
"Those determined to find fault with this bill will always be able to look at a narrow slice of it and find something they don't like," the president said. "If you want to kill the bill, if you don't want to do what's right for America, you can pick one little aspect out of it.
"You can use it to frighten people," Mr. Bush said, "or you can show leadership and solve this problem once and for all."
The bill would give temporary legal status to millions of unlawful immigrants, provided they came forward, paid a fine and underwent criminal background checks. To apply for a green card, evidence of legal residency, they would have to pay another fine, learn English, return to their home country and wait in line.
The plan also would create a guest worker program. It would allow foreign laborers to come to the United States on a temporary basis, but with no guarantee they eventually could gain citizenship.
Both the new visa plan and the temporary worker program are contingent on other steps coming first. Those include fencing and barriers along the Mexico border, the hiring of more Border Patrol agents and the completion of an identification system to verify employees' legal status.
The legislation also would reshape future immigration decisions. A new point system would prioritize skills and education over family in deciding who can immigrate.
Georgia's senators both played leading roles in producing Mr. Bush's deal with the Senate. However, they have also said they may not support the final bill, depending upon how it is amended.