An unlikely pair of senators has teamed up to mount an assault on Colorado’s landmark educator evaluation law, which still hasn’t been fully put into practice after six years.

School districts could drop use of student academic growth data in teacher evaluations under a bill introduced Friday by Sens. Mike Merrifield and Vicki Marble.

The proposal, Senate Bill 16-105, also would give districts discretion to eliminate annual ratings for teachers who are rating effective or highly effective.

The prime sponsors are something of a political odd couple, liberal Democrat Merrifield of Colorado Springs and conservative Republican Marble of Fort Collins.

But the two have made common cause in opposition to state standardized testing and to using testing data to evaluate educators. Merrifield, a retired music teacher, is a longtime opponent of the landmark evaluation system created by a 2010 law. Marble is the legislature’s most vocal critic of the state testing system.

Their bill going after the educator effectiveness law had been expected, and they’ve also teamed up on Senate Bill 16-005, a measure to eliminate 9th grade testing.

State law requires that principals and teachers be evaluated annually and that at least 50 percent of those evaluations be based on student academic growth as determined by state test scores and other district and classroom measures.

Because the state switched to the new PARCC tests in 2015, no state growth data is being used to evaluate teachers this school year. Districts instead must use locally chosen tests and other measures.

The new bill would eliminate the academic growth requirement but let districts use student growth for up to 20 percent of evaluations if they choose. Districts that have their own evaluation systems could exempt principals and teachers from annual reviews if they’ve previously been rated effective or highly effective. They would have to be evaluated at least every three years.

Such a major change in the evaluation system is considered a long shot this session and likely would face a gubernatorial veto if it passed both houses.

Merrifield, as a solo sponsor, introduced a similar bill in 2015. It never got out of the Senate Education Committee.

Merrifield and Marble sit on that nine-member committee. Two other panel members, Democratic Sens. Andy Kerr of Lakewood and Nancy Todd of Aurora, are cosponsors of SB 16-105. There’s no House sponsor yet.

Two other education bills were introduced Friday.

Senate Bill 16-101 would create a five-member ethics commission within the Department of Education to hear ethics complaints against members of school district and charter boards. Kerr is the prime Senate sponsor.

Senate Bill 16-104 proposes several programs to encourage teachers to work in rural school districts, including creation of rural education centers, stipends for student teachers, cadet programs in rural districts to encourage high school students to become teachers and financial support of rural teachers who seek board certification or credentials for teaching concurrent college courses. The introduced version doesn’t include a price tag. Todd is the prime Senate sponsor, teamed with Rep. Jon Becker, R-Fort Morgan, in the House.