Passports should be mandatory for all in U.S.
Mandatory passports for every adult living the U.S. would solve a lot of illegal immigration problems. If you had to show a passport to get a job, receive government aid, receive non-life-threatening ER medical care or any other applicable uses, then that would force illegal immigrants to voluntarily leave the U.S. because that would take away the reasons they have for being here illegally.
The infrastructure is already in place. A passport is better than a national ID card or a Social Security card. This idea is not amnesty or the Dream Act. I think it is a better idea than any politician has given as a fix for the illegal immigration problem.