Gun rights activists are turning up the heat on Gov. Gary Herbert, fearing the governor is on the verge of vetoing a bill to exempt Utah-made guns from federal firearms laws.

The group Gun Owners of Utah [Go Utah!] put out an urgent action alert stating that Herbert is "seriously considering" a veto of SB11, and urging members to call the governor's office to support the measure.

"We need to make the Governor's phones ring off the hook," the alert said. "If you're so inclined, feel free to mention that you will not vote for him if he vetoes SB 11."

Legislative attorneys have said there is a high probability the measure challenging the federal regulations would be found unconstitutional and Herbert's office has said he is concerned about the potential cost of litigation.

But GO Utah! argues there would be no costs to the state in defending the bill and believes Herbert understands that.

"We speculate that his real motivation for vetoing SB 11 might be a simple lack of interest in protecting the right to keep and bear arms against federal infringement," the GO Utah! alert said.

The governor's spokeswoman, Angie Welling, said Wednesday the governor "fully supports the concept of SB11 and, generally, other measures moving through the Legislature that assert Utah's rights over the federal government."

"However, he also told sponsors of SB11 that he continues to have constitutional concerns with the bill and intends to fully analyze and review the legislation before taking action on it," she said.

The GO Utah! action alert is based on an account of the meeting from Clark Aposhian of the Utah Shooting Sports Council -- who was not actually at the meeting, which only included the governor and legislators.

Rep. Carl Wimmer, R-Herriman, who was at the meeting, said he is "confident" Herbert will sign the bill.

"I think the governor is just being very deliberative, as he should be, and I fully anticipate that in the end he'll support the bill," Wimmer said. "He wants to make sure it's done the correct way."

Aposhian said the case that supporters are trying to make to the governor is that signing the bill won't cost the state money.

The Utah legislation is patterned after a bill that passed in Montana. Currently the Montana Shooting Sports Association is suing the federal government over enactment of the legislation, but the state is not a party, Aposhian said.

Law firms in Montana have taken the case free of charge, he said.

"This is not going to cost any money," Aposhian said. "He is with us completely on the entire states' rights issue the bill advances, but we want to make sure he has every reason not to worry about the potential the state may end up footing the bill."

A call to the Montana Attorney General's office was not returned Wednesday.

The U.S. Department of Justice has asked a judge to dismiss the case. The agency argues state law is pre-empted by federal firearms regulation and, according to The Associated Press, also contends that the gun-rights advocates have no legal standing to bring the suit.