Here's a look at the House bill, approved in December by a vote of 239-182, and the proposed compromise that collapsed in the Senate on Friday.
HOUSE IMMIGRATION BILL WOULD:
* Create a felony, "unlawful presence," for anyone who is in the United States in violation of immigration laws. Violators could spend a year and a day in prison.
* Make it a crime, subject to as long as five years in prison, to assist, encourage, direct or induce a person to reside or remain in the United States illegally.
* Authorize double-layered, reinforced fencing intermittently from near Tecate, Calif., to near Brownsville, Texas. Construction would move most quickly between Calexico, Calif., and Douglas, Ariz., and around Laredo, Texas. A study would be conducted of a potential "state of the art barrier system" along the U.S.-Canada border.
* Starting Oct. 1, anyone caught trying to enter the country illegally would be detained and sent home. Mandatory detention would not apply to Cubans. The government would "explore all possible options" to increase detention bed space.
PROPOSED SENATE COMPROMISE WOULD:
* Allow illegal immigrants in the country five years or longer to remain and apply for legal, permanent residency after working six more years. Illegal immigrants here two to five years would get three years to gather material to qualify for a change in status. Illegal immigrants here less than two years would have to leave and then apply for temporary worker visas or legal permanent residency.
* Create a guest worker program for an estimated 1.5 million immigrant farm workers, who also could earn legal permanent residency. Illegal immigrants who can show they've worked seasonally in U.S. agriculture for three to five years could apply, as could foreigners who have never worked here.
* Add as many as 14,000 Border Patrol agents to the force of 11,300 by 2011.
* Authorize unmanned vehicles, cameras and sensors to monitor the U.S.-Mexican border, and more detention facilities for illegal immigrants.
* Allow states to charge in-state tuition to illegal immigrant students with high school diplomas or GEDs and no criminal record. They also must meet other criteria.