A tuition tax credits bill has been revamped a second time to eliminate all but the poorest private school students from participating.

Meanwhile, a poll conducted for the Deseret Morning News and KSL-TV found Utah residents warm to the idea of tuition tax credits based on income, but most still oppose the measure.

Second substitute HB39 would make ineligible anyone enrolled in private school as of Jan. 1, except families whose income qualifies for reduced-price school lunch.

Federal guidelines, which vary by income and family size, would put that earnings threshold at $34,873 for a family of four.

All public school students would be eligible.

Fiscal analyses showed that including private-school kids would cost "more than I was willing to embrace," said the bill's sponsor, Rep. Jim Ferrin, R-Orem.

"(This) has the effect of phasing them in over 13 years, which has been demonstrated in past bills as doable."

The State Office of Education estimated the first substitute bill would cost the state $16.2 million next fiscal year.

Utah Education Association President Pat Rusk believes the bill will change "until (they) get something that seems innocuous."

"It's a very expensive proposition, no matter how you cut and paste it," she said.

Second substitute HB39, co-sponsored by Rep. Steve Mascaro, R-West Jordan, still would give a means-tested tuition tax credit based on federal reduced-price school lunch scales and ranging from $500 to $3,750. Families generally making more than $100,000 a year would get nothing. The bill also includes $1.5 million to bail out school districts financially hurt by the credits and measures that would make participating private schools publicly accountable for academic performance, teacher credentials and other factors.

The financial impact of the latest version is being studied.

Public school officials and teachers unions fear schools would lose money under the credits, as all state income tax revenues fund education. Bill supporters say the credits would save the state money, as credits would be less than per-student spending and would divert some of the coming enrollment boom.

A Dan Jones & Associates survey found 43 percent of Utah residents strongly or somewhat favor a tuition tax credit bill based on income. That's up from the 36 percent generally favoring tuition tax credits in an early January poll.

But 50 percent said they somewhat or strongly oppose a tuition tax credit bill based on income, and 7 percent said they didn't know.

Public approval varies by income level.