Colorado state senators fought off efforts Thursday night to tone down controversial teacher reform legislation—Senate Bill 191, passing what Senator Rollie Heath, a Boulder Democrat, notes would be a “monumental change” for state education.

The bill, which is expected to pass a third reading in the Senate today before going to Colorado’s House next week, would marry evaluations for principals and teachers to student academic growth and would change how teachers receive and retain tenure, according to The Denver Post.

“This is one of those right-side-of-history votes,” says Senator Josh Penry, a Grand Junction Republican, of the legislation, which has divided Democrats and left the teachers union scrambling in opposition.

As Education News Coloradonotes, the bill is similar to legislation being discussed in other states, which is part of a national trend to reform how educators’ work is evaluated. Though the legislation could help Colorado obtain millions of dollars in federal “Race to the Top” funding, little debate has centered on that issue.