DENVER -- Fewer immigrant workers are coming to Colorado because of tougher state laws, but the agricultural, ski and hotel industries are having a tougher time finding seasonal workers, Gov. Bill Ritter said Thursday.

Without citing statistics, Ritter said employers around the state complain they face worker shortages because of laws passed in 2006 to fight illegal immigration. He said efforts to fortify guest worker programs would offer a solution.

"I quite frankly think that one of the people who understood this issue best in public life was (President) George Bush," Ritter said. "George Bush had a real desire to tackle this issue."

One law created a state patrol unit with the authority to enforce federal immigration law during routine patrols and curb human smuggling. Another barred immigrants from receiving some state services unless they can prove they are in the country legally. Also in 2006, lawmakers passed a bill requiring police to report anyone they believe to be in the country illegally to Immigration and Customs Enforcement.

Ritter noted that federal changes to seasonal worker visas means ski resort employees are losing their visas sooner. Anecdotally, he said Vail could have stayed open another month last year if its guest workers had lengthier visas.

At a minimum, Ritter said, successful immigration policy would "bring illegal immigrants out of the shadows."

"Find a way to acknowledge their existence here and the fact they're employed and contributing to the economy," he said.

Ritter spoke to a University of Denver panel studying immigration. The panel will issue a report with policy recommendations to the state Legislature in December, said Dave Brendsel, a DU spokesman.

Ritter, a Democrat who was elected in 2006, was criticized during his campaign by opponent Bob Beauprez for plea bargains he reached with illegal immigrants while serving as Denver's district attorney.