Waller's candidacy was endorsed by the Denver Post and the Colorado Springs Independent, [8] and he won election to the legislature with 66 percent of votes cast.

[10] Waller sponsored legislation to require disclosure on clothes collection bins operated by for-profit companies, to include a new derivative of methamphetamine to Colorado's list of banned drugs, and to exclude dry-ice bombs from a felony list of explosives, and to allow homeschooled students to enroll in college classes.

A bipartisan effort with Democrat Pete Lee passed legislation that moved forward the state's restorative justice programs, albeit with compromises acknowledged on Waller's part.

Following a low performance in the primary on June 24, Waller withdrew from the race and endorsed Cynthia Coffman, who went on to win the November election.

Waller took his seat early due to his predecessor, Amy Lathen, exiting her position for another job in June 2016.

[17] He faced Senior Deputy District Attorney Michael Allen in the GOP primary, held June 30, 2020.