As a labor contractor in the nation's winter lettuce capital, Francisco Chavez struggles to hire enough workers to pick and package the produce.

Last year, ripe romaine sometimes went bad in the fields around Yuma, Ariz., because Chavez didn't have enough people to harvest the crop, which must be picked by hand. "That's my challenge — to get the crews," he said.

Such complaints are becoming so common that lawmakers in Arizona and Colorado are considering creating their own guest-worker programs to attract more immigrant laborers. It's unclear whether states have the authority to adopt such measures, but legislators are tired of waiting for Congress to overhaul the immigration system — and they are taking matters into their own hands.

State Sen. Abel Tapia, the Democratic co-author of the Colorado proposal, lashed out at Washington: "You had your chance to do a comprehensive immigration package a year ago, and you didn't do it, and I can't imagine that you will have anything by 2010, so what are we to do in the meantime?"

The federal government has run guest-worker programs for more than a century, but congressional efforts to overhaul the system stalled in 2006 and 2007.

The Arizona proposal aims to create a program run entirely by the state. Employers could recruit workers through Mexican consulates if they can document a labor shortage and unsuccessful efforts to find local employees.

If approved, the measure would admit an unlimited number of workers in a wide range of industries.

The Colorado proposal is intended to help chili, tomato and watermelon farmers. It's aimed at eliminating bottlenecks that slow federal applications for immigrant laborers. As an incentive for workers to return to their homelands, Colorado farmers would be required to withhold 20 percent of workers' wages and send the money after the workers move home.

The Arizona bill got unanimous approval last month from a legislative committee.

A sponsor of the Colorado proposal said she may scale back the bill because of opposition, reducing it to a program that would let the state hire labor firms in Mexico to find workers and help resolve procedural problems at U.S. consulates there.

Neither measure has come to a vote before the full House or Senate.

Immigration law experts said states don't have the foreign-policy power to negotiate guest-worker agreements, but Congress could grant them permission to do so.

Democratic U.S. Rep. Silvestre Reyes of Texas, a former Border Patrol boss who supports revamping the nation's guest-worker programs, said it's unlikely states would get the necessary permission to arrange their own foreign labor.

He also said it's ironic that Arizona and Colorado are so eager for cheap foreign labor because in recent years both states have cracked down on illegal immigration.

"I'd say to the states: 'You can't have it both ways,'" Reyes said.

Kris Kobach, a law professor at the University of Missouri at Kansas City and an advocate of expanding state and local immigration efforts, said the proposals could never hold up in court. He said the Supreme Court has ruled that states cannot impose additional conditions on immigrants who are working legally in the United States.

Aside from the legal barriers, state-run guest-worker programs would probably face another hurdle: Businesses in other states that lean on Congress to sink the idea, because their rivals could pay lower wages and get a steadier supply of labor.

The Arizona bill is also opposed by some immigrant-rights groups, which have backed immigration-reform efforts but fear the state plans would exploit immigrants.

Hector Yturralde, president of Somos America, a coalition of immigrant-advocacy groups that has staged protests in Phoenix, likened the Arizona proposal to the "bracero" program that brought in Mexican farm laborers during World War II. It ended in 1964 amid allegations of worker abuse.

"It's indentured labor," Yturralde said, referring to the Arizona proposal.

Republican state Rep. Bill Konopnicki, a restaurant owner and an author of the bill, said the labor shortage in Arizona had been mounting for several years. It grew worse after passage of a new state law that punishes businesses for knowingly hiring illegal immigrants. That law has pressured many immigrants to leave.

Francisco Chavez, the Arizona labor contractor, said the 2007 labor shortage in the lettuce fields was eased by shrinking demand for lettuce that prompted farmers to plant less. But if demand rises, he said, labor contractors won't have enough workers, and prices could spike for consumers.

If field hands can't pick enough produce, Chavez said, shoppers "won't be able to have a salad, because there is no way to get it into the market."