A union-backed bill that would create a fund that cash-strapped districts could tap for teacher pay raises advanced out of the Senate Education Committee Wednesday on a party-line vote, though not before lawmakers of both parties raised questions.

Republicans on the committee said that by also including hourly workers like bus drivers and school secretaries, the money in the fund would be stretched so thin it wouldn’t do much for teacher pay. And state Sen. Jeff Bridges, a Greenwood Village Democrat, asked whether the bill would inadvertently create incentives for local communities not to tax themselves.

The bill calls for at least $15 million a year to be set aside from state lands proceeds. Districts with low teacher salaries or hourly wages could apply for those funds to raise pay. Those districts would eventually be responsible for assuming the ongoing costs of the raises. The specific criteria that would be used to determine eligibility is still being discussed.

A few hours later, Democrats on the Senate State, Military, & Veterans Affairs Committee rejected a different teacher pay bill that would have given out bonuses up to $12,000 to highly effective teachers who took jobs in schools with persistent low test scores. State Affairs is known as a “kill committee,” a place where bills die for largely partisan reasons.

Though the bonus bill had a Democratic co-sponsor, the outcome largely reflected ideological differences over the best way to pay teachers: raising wages across the board or targeting state funds to teachers who are making the most difference.

Teachers unions generally oppose bonus pay or performance pay, instead preferring more predictable salary schedules that reward longevity and educational credits. Colorado Education Association President Amie Baca-Oehlert said the teacher rating system was never designed to be used for merit pay and that teaching is a team activity, in which no one person is responsible for the success or failure of students.

State Sen. Kevin Priola, a Brighton Republican and sponsor of the bonus pay bill, said he had hoped the idea would get a fair hearing.

“If this were to be adopted, I believe it would help, at the margin, those teachers who decide to stay (in challenging schools),” he said. “This will create a ripple effect that will benefit not only the students in the room but the culture of the school.”

The bonus bill would have created a $4 million fund for bonuses for teachers who get top ratings and either move to or stay in a low-performing school.

“As an instructor, I believe that all students and all schools deserve good teachers who can push them to improve their performance,” said Anne Keke, a teacher at Colorado Early Colleges in Aurora and a member of the African Leadership Group, as she testified in support of the bill.

Katie Martinez of the advocacy group A Plus Colorado pointed to research that has found bonus pay effective in keeping good teachers at high-poverty schools. Bonus pay was a major point of contention in the Denver teachers strike last year, with research showing mixed results and teachers divided. The Aurora school district has also experimented with bonuses or stipends for certain hard-to-staff positions.

A third teacher pay bill sponsored by Republican state Sen. Paul Lundeen, which also calls for bonuses for highly effective teachers, has yet to receive a hearing.