Officials said the study is consistent with similar analyses performed in Texas, which has not adopted an Oklahoma-style law.

Hispanic leaders have estimated that more than 20,000 undocumented workers, mostly in the Tulsa area, fled the state ahead of the bill taking effect.

Terrill questioned the study’s conclusions after a cursory review of it. He said his legislation was geared toward “an attrition through enforcement approach,” with no mass exodus of undocumented workers expected.

He said, however, the intent of the bill was to have illegal workers leave Oklahoma for other states and there is antidotal evidence that is happening. “We still have no hard numbers,” he said.

Terrill called the report “one of the best reports that money can buy to take shots at House Bill 1804.”

“This debate is about a whole lot more than just economics,” he said. “It is about defending the rule of law, it is about upholding our state and national sovereignty and it’s also about the immorality of employing cheap, illegal labor.”

The lawmaker said an anti-illegal immigration group has estimated Oklahoma loses more than $200 million in state revenue through education, medical and other benefits paid to illegal workers and their families.

Terrill said the OBA report does not account for those benefits in projecting economic losses to the state.

“Even if a few businesses are impacted by a departure of illegals from Oklahoma, this will be more than offset by the positives to the taxpayers of Oklahoma,” said Sen. James A. Williamson, R-Tulsa, Senate sponsor of the legislation.

The U.S. Chamber of Commerce has filed a federal lawsuit challenging the Oklahoma statute as interfering with federal immigration law.

A spokesman for Gov. Brad Henry, who signed the bill into law, had no immediate comment on the study. Henry has urged lawmakers to monitor the effect of the law for unintended consequences.