At stake is a flat-rate option for income tax filers and a transportation funding measure that would allow counties statewide to use sales tax increases to upgrade commuter trains, airports and roads.

One of the last-minute tweaks, income adjustments for inflation, is one that will make the legislation something even Democrats can swallow - if not love.

The income tax proposal, which Gov. Jon Huntsman Jr. is calling a first step in comprehensive reform, would broaden the brackets of the existing code. It also would allow taxpayers the choice of paying at a flat tax rate of about 5.4 percent, but without deductions or credits.

Critics say the proposal is not real reform because less than 5 percent of filers, mostly the rich, would benefit from the flat-tax option. The vast majority of Utahns would stay under the "traditional" bracketed structure with its top rate of 7 percent.

Many lawmakers, Democrat and Republican, have been lobbying to add inflation indexing to the bracket system, something Democrats have advocated for decades.

Sen. Curt Bramble, chairman of the Senate Revenue and Taxation Committee, says building in inflation adjustments will increase the cost of the dual-tax change from $70 million to about $76 million. But, Bramble says, "With indexing, we won't lose the gains we make [under the new system] after a few years."

The minority party has been cold to the income tax change because its $70 million tax cut comes from public school money. They are skeptical of Huntsman's promise that the state will reap much more education revenue through economic growth.

"Without indexing, I don't think any Democrats would support the income tax plan," said Rep. Brad King, D-Price. "The indexing makes me think there actually will be some reform in it."

Dorothy Owen, a former member of the Utah Tax Review Commission, said the inflation bracketing tweak is "a big deal." A 1999 study found that Utahns paid $300 million more in taxes that year because of inflation-driven "bracket creep" over the previous 30 years, Owen said.

"There are a lot of political reasons not to index for inflation," she said. "If you don't index, every year you get more tax money. You never have to raise taxes - inflation will do it for you."

Huntsman and his supporters say the flat tax option would help Utah compete with its neighbors for businesses. Under their theory, economic growth generated by additional jobs would continue to energize the economy and provide additional school funding.

Huntsman spokesman Mike Mower says the governor is confident the income tax proposal - with inflation indexing - and the transportation tax bill will be in the special session, most likely to be Sept. 19.