Four years after receiving permission to tie teacher pay to their performance, some school districts are moving away from paying teachers based on their evaluations.

Four districts changed their teacher pay plans in the first year after legislators passed a 2010 law to allow districts to tie salaries to teacher evaluations. The law was part of Tennessee’s successful effort to win federal education funding through the Obama administration’s Race to the Top grant program.

That number shot up to 57 districts — out of 142 statewide — in 2014 but fell this year to 54, state officials told lawmakers in Nashville on Wednesday.

Officials did not say which districts had opted out, or why the pace of districts adopting performance-pay plans had slowed.

But the stagnation could signal that superintendents and school boards are hesitant about putting too much stock in the state’s teacher evaluation system, which was among the first in the nation to use standardized test scores.

Districts that have adopted merit-pay plans have seen varying amounts of resistance. When Shelby County Schools Superintendent Dorsey Hopson proposed merit pay earlier this year, he faced mass protests from teachers, causing him to table the idea.

But in Kingsport City Schools, which adopted merit pay in 2014, “pushback was almost zero,” Superintendent Lyle Ailshie said during Wednesday’s Basic Education Program (BEP) meeting. Ailshie said teachers were supportive of the plan because they helped draft it through a task force that involved teachers from all of the district’s schools.

“It’s not perfect yet, and it may never be … but so far it seems to be working for us,” he said.

Merit pay is just one of several options available to districts to differentiate pay under a rule that the State Board of Education revised in 2013. The most common option in Tennessee is paying teachers more to teach at high-needs schools, or in subjects where there is a dearth of qualified teachers.

Officials at the Board and the Department of Education view differentiated pay as a means to attract and retain effective teachers, whom they say do not always have experience or advanced degrees.

But many educators say teacher pay just needs to be raised in general.

A committee that reviews how Tennessee funds its schools has recommended every year for nearly a decade that the state put more money toward teacher salaries, an urging that has gone largely unheeded.

That changed this year, when Gov. Bill Haslam pledged $170 million toward his goal of making Tennessee teacher salaries among the fastest-growing in the United States. (He had reneged on a promise to raise salaries last year.)

Teachers in 75 percent of districts saw raises this year, according to Sylvia Flowers, director of educator talent for the state Department of Education.

Most of the other districts put that money toward their differentiated pay plans, meaning only some teachers got bonuses.

But even with the slight bumps allowed by Haslam’s increase, district officials still say that funding for salaries is an issue. Inadequate teacher pay is at the center of two active lawsuits against the state.

And Ailshie said that more funding for salaries is crucial to attracting teaching talent, differentiated pay or no.

“The key will be that the state put additional funds into [salaries],” he said.