They were backed Wednesday by parents of children who have been exploited, including Ed Smart, the father of Salt Lake City kidnapping victim Elizabeth Smart, and John Walsh of "America's Most Wanted."

"This is common sense," said Hatch. "Those who break such a sacred trust and harm our children - no matter who they are, where they're from, or where they commit their crime - should have to voluntarily make their whereabouts known or subject themselves to additional jail time."

Nearly 550,000 offenders are registered nationwide, but an estimated 100,000 sex offenders have failed to register with their states as required, said Ernie Allen, president and CEO of the National Center for Missing and Exploited Children.

There are about 8,000 sex offenders in the Utah database (http://www.cr.ex.state.ut .us/community/sexoffenders/).

"We need to completely change the way we treat sex offenders," said Rep. Mark Foley, R-Fla., the House sponsor of the bill. "They are not petty criminals. They prey on our children like animals and will continue to do so until we stop them."

The legislation would require offenders to update their registration in person every six months, submit DNA to a national database, require released offenders to wear monitoring bracelets for a period of time, and impose new notification requirements on offenders when they move or change jobs.

"We'll make prey out of predators," Foley said.

Jack King, spokesman for the National Association of Criminal Defense Lawyers, said Foley's proposal neglects the most effective way to prevent repeat offenses - treatment.

"Expense and practicality aside, if you're going to spend that kind of money, studies have shown that the best prevention for sex offenders is treatment," he said. "If a person is compulsive and has very little impulse control, this guy isn't going to wait to get his ankle bracelet off. If he loses control, he's going to commit the crime and the ankle bracelet, it's not going to stop him."

The bill would not have affected the man who prosecutors say kidnapped Elizabeth Smart. Brian David Mitchell did not have a record of sex crimes before he kidnapped Smart. But Ed Smart said he wants to see the bill passed to help protect other children.

"There is no cure for sex offenders. They can learn to control it, but if they choose to or not is a whole different issue," Smart said. "We, as a society, need to make them responsible for it."

Hatch and Foley said they expect Congress will move quickly on the bill. Foley said the federal government would provide states with whatever money it took to implement the new law.

There have been a series of recent, high-profile kidnappings. In Florida, 13-year-old Sarah Lunde was kidnapped and killed last month. And 9-year-old Jessica Lunsford was kidnapped on Feb. 23 and killed. Convicted sex offenders have been charged with murder in each case.

"The system doesn't work for children in this country. The American public is sick of seeing these lowlifes roam the streets preying on our children," Walsh said. "Sarah Lunde and Jessica Lunsford might be here today if this bill was passed a year ago."

Bill's provisions

* Register: Sex offenders must do so before they are released, rather than after release.

* Re-register: In person twice a year, rather than annually. Violent offenders must re-register every three months.

* Notice of changes: Address or employment changes must be filed within three days, rather than 10. State officials must also notify the new state if an offender moves.

* Social Security numbers: Offenders must include their Social Security number to ease tracking.

* Tracking devices: First-time offenders must wear a tracking ankle bracelet during their supervised release and must wear one permanently after a second offense. Violent predators must wear a tracking bracelet for life.

* Data management: States must manage registries. Some local governments now run registries.

* DNA identity: Establishes a sex offender DNA database.

* Failure to register: Makes it a felony and, for immigrants, a deportable offense.

Source: Sen. Orrin Hatch, Rep. Mark Foley