DENVER — State lawmakers approved a measure late Monday that would force a million people receiving state or federal aid to verify their citizenship, part of a package of bills dealing with illegal immigration that Democrats called the toughest in the nation.

The measure would deny most non-emergency state benefits to illegal immigrants 18 years old and older — forcing people to prove legal residency when applying for benefits or renewing their eligibility. The measure passed the state Senate 22–13 and the House 48–15. Both are controlled by Democrats.

“At the end of the day, everybody who serves in this building as senators or representatives knows we’re making Colorado history,” said the bill’s sponsor, Senate President Joan Fitz-Gerald. “We want to be able to look in the mirror and say we did legislation that is tough, enforceable, and humane.”

Republicans said the bill didn’t go far enough, and left glaring loopholes, including allowing benefits for minors and denying voters the chance to have a direct say on the issue. The bill would apply to Medicare, Medicaid, unemployment insurance, energy assistance programs and aging and adult services. Republican Governor Owens said an estimated 50,000 illegal immigrants could be thrown out of those programs.

“It simply puts teeth into existing federal regulations,” Mr. Owens said.