A Democratic lawmaker wants to get beyond the rhetoric that often surrounds the debate over undocumented immigrants with a state study that would calculate not only their costs but also the economic benefits they bring.

The Senate agreed Friday to let Sen. Scott McCoy, D-Salt Lake, open a late bill file to call for "a study of the economic and budgetary impact of undocumented immigrants on the state of Utah." His resolution has yet to be drafted.

"We always hear about, 'Oh, my gosh, they're such a drain on services.' We hear that there is a budgetary impact. But that is only one side of the coin," McCoy said. "I think they are part of economic development and economic prosperity."

A group of Latino community leaders delivered a letter to Gov. Jon Huntsman Jr. this week requesting such an audit. That request was referred to the Legislature because that is the body that generally requests such audits, said Mike Mower, the governor's spokesman. "Generally speaking, more information is helpful," Mower said.

Tony Yapias, director of Proyecto Latino de Utah, has also been pitching the idea to lawmakers and said he was "very encouraged" that the Senate is taking a step toward such an audit.

"The Legislature is beginning to realize how important it is to have something concrete in terms of numbers," Yapias said. "That way we can be talking with real numbers."

Yapias said the Latino leaders' request for a comprehensive study was in response to a legislative audit under way, which Sen. Margaret Dayton, R-Orem, requested, to look at the costs of educating undocumented children in Utah's schools. The audit will only be looking at general education costs because schools legally can't ask a child's immigration status.

McCoy said he has not seen Dayton's request.

"Here's the danger," McCoy said. "You only audit one side of the ledger, you're not going to get the full picture."

McCoy said the purpose of the comprehensive study is to make sure "we have the best, most accurate information about what the undocumented immigrant population means to the state. It's one thing to say they take a lot of services and don't pay taxes. But what are they contributing?"

The study likely wouldn't be completed until the 2009 Legislature. McCoy said a similar study done in Texas showed that undocumented immigrants produced $1.58 billion in state revenues — more than the amount of state services that they received.

However, the same study found "local governments bore the burden of $1.44 billion in uncompensated health-care costs and local law enforcement costs not paid for by the state."

There are several bills dealing with undocumented immigrants pending this session. McCoy said the study's findings will be useful as lawmakers debate such bills in the future, likely including another attempt at repealing a law allowing them to pay in-state tuition at Utah's universities and colleges. That repeal could resurface again this session after it narrowly died in the House this week.