GOP legislative leaders have set Sept. 5 for a committee hearing and party caucuses — and maybe a meeting of all lawmakers — to discuss the latest plans for a "dual track" state income tax system and a sales tax hike for TRAX transit line extensions.

The majority party caucuses will determine whether there's enough support for Gov. Jon Huntsman Jr. to call a mid-September special session that could result in at least a $70 million income tax cut — and a sales tax hike on the November ballot in Salt Lake County.

"It is very likely there will be a special session to address the dual tax system as a well as the transit hike," Huntsman's spokesman, Mike Mower, said Wednesday. The governor met late in the day with legislative leaders and discussed strategy.

They are looking for a way for Huntsman and other proponents to pitch the plan to the entire Legislature following an 8 a.m. meeting of the Revenue and Taxation Interim Committee, Senate President John Valentine, R-Orem, said. Any such gathering of lawmakers would be informal but would be an opportunity for them to have any questions or concerns addressed before the caucus vote.

That could be key to winning enough support to justify a special session. "This really is the administration's proposal, and it takes some selling on their part to make sure tax reform goes forward, not just a tax cut," Valentine said.

There's plenty of work to be done, especially on the new income tax plan, which would affect income earned in 2006. "The governor is very focused on making certain that the dual tax system is adopted and the entire administrative team is working hard toward that end," Mower said.

Huntsman — and legislative leaders — support creating an income tax structure that would give taxpayers a choice of paying either a flat-tax rate with no deductions or staying in an adjusted version of the current tax system.

The governor, who has said offering a flat-tax option would help encourage economic development in the state, prefers the version of the "dual track" system that would give Utahns a $70 million tax cut because "that's what's on the table," Mower said.

The 2006 Legislature failed in its final hours to pass a $70 million income tax cut, part of a $160 million tax cut plan agreed to by Huntsman and legislative leaders that also included reducing the sales tax on food by $70 million and business taxes by $20 million.

Valentine said legislative leaders are also backing a $70 million cut. But some conservative lawmakers have talked about a bigger tax cut after the budget year ended June 30 with a record $351 million tax surplus, much of it in the personal income tax. One of the options under consideration would boost the income tax cut to $122 million.