SALT LAKE CITY — Backers of the Our Schools Now citizens initiative that would raise taxes some $700 million for education are expected to kick off their campaign next week to win a place on the November 2018 ballot.

Although Utah Jazz owner Gail Miller and the other business leaders behind the initiative initially announced they wanted to raise the income tax rate by seven-eighths of 1 percent, they're now expected to also seek a state sales tax increase.

The initiative language that will be submitted to the lieutenant governor's office is believed to ask voters to approve boosting the state sales tax rate from 4.7 percent to 5.2 percent, and the state income tax rate from 5 percent to 5.5 percent.

Austin Cox, campaign manager for the initiative, would not comment Thursday on the numbers.

"We've engaged in conversations with key stakeholders over the past several months, and we are anxious to release additional details soon. Also, we're confident that our newest version of the initiative will receive even greater support," he said.

Cox added that "some provisions are still being considered," and more details will be shared next week.

Initiative backers were approached earlier this year about seeking an increase in sales tax rather than income tax because lawmakers were worried about the impact of the original proposal on economic development.

Bob Marquardt, a member of the initiative group's executive committee, told the Deseret News in February that Our Schools Now had "been encouraged to switch from income to sales tax. We're not completely opposed to at least talking about that."

House and Senate leaders had hoped to stop the initiative from going forward by passing a tax increase during the 2017 Legislature, but a plan that would have restored the state sales tax on food fell apart in the final days of the session.

Senate President Wayne Niederhauser, R-Sandy, said Thursday he did not know the specifics of the latest initiative proposal.

"Any income tax increase, I think, is the wrong way to go," Niederhauser said. "Income tax is a tax on productivity. We don't want less productivity. We're trying to keep an economic engine running."

The Senate leader said there is "plenty of headroom in the sales tax" to raise whatever is needed for schools and suggested the estimated $700 million that would come from the initiative may be more than lawmakers could spend.

"I hope they're looking at something incremental," he said, noting that going to voters with a proposal that includes two tax increases "makes it more difficult to pass. It makes it a little more complicated and raises more questions."

Niederhauser said lawmakers are working during the interim on a plan to replace the sales tax earmarks for transportation with gas tax increases and other targeted revenue boosts over five years to eventually free up some $600 million for schools.

"Politically, this is a very difficult thing for the Legislature to do," the Senate president said of raising taxes. But he said the possibility of an initiative going before voters in 2018 "gives us some motivation to do something."

The initiative launch will come as school districts along the Wasatch Front are raising starting salaries for teachers to $40,000 or more — just a first step, according to Utah Education Association President Heidi Matthews.

"We're behind the Our Schools Now initiative wholeheartedly," Matthews said, describing it as giving Utahns the opportunity "to say, 'We value education. We value education across the state, and we're willing to invest in it.'"

The initiative "could be enough to send marching orders to the Legislature to develop a long-term funding solution that reflects the values of the people," already seen in the teacher raises, she said.

Initiative backers will have until April 15 to collect the more than 113,000 signatures from voters in at least 26 of the 29 state Senate districts that are needed to qualify for the November 2018 general election.

Before Our Schools Now can begin circulating petitions, however, the initiative must be filed with the lieutenant governor's office and public hearings must be held throughout the state.

Contributing: Ladd Egan