Franchot, who has broken with other Democratic leaders over tax issues as well as gambling, said the bill represents an attempt at "political payback that jeopardizes a core government function."
"We're in the heart of our tax season and this is just an unbelievably unnecessary distraction," Franchot said. "It's not a new game by Annapolis standards, but this type of legislation is not a game."
The comptroller said transferring the alcohol, tobacco and fuel tax collection functions would be difficult and expensive because workers in his office perform jobs that cut across lines of which tax is being enforced. He said the legislation could also raise constitutional questions.
Franchot said his agency has recently gone through two audits with no findings of problems.
"We are nationally recognized for effectiveness and efficiency. Even my critics concede we have a very well run agency," he said.
Davis, a Prince George's County Democrat, said he has no reason to believe the agency is doing a subpar job. All he wants to do, Davis said, is explore whether shifting the comptroller's functions to the department would be more cost-effective. He said he has not looked into the question of constitutionality.
The lawmaker denied his bill has anything to do with retaliation against Franchot. Davis is an employee of Prince George's County, where County Executive Rushern L. Baker III was a leading proponent of the casino expansion bill Franchot vocally opposed in television ads. The expansion referendum question passed.
"It's unfortunate if he thinks a legitimate policy discussion revolves around him," said Davis, who chairs the House Economic Committee and is a member of Speaker Michael E. Busch's leadership team.
Davis, who formerly worked for the department, said his bill was strictly his own idea. If it comes back with a high cost estimate, as the comptroller predicted it would, the lawmaker said the idea shouldn't go forward.
"I'm not married to it," Davis said. "If it's not fiscally prudent, we absolutely should abandon it."
Maureen O'Connor, a spokeswoman for the department, said the agency's legislative staff is studying the legislation.