A member of the Republican Party of Minnesota, he represented District 35, which includes portions of Anoka County in the northern Twin Cities metropolitan area.
"[3] Petersen was the chief author of legislation to link teacher evaluations to student achievement for the first time in state history.
[citation needed] The Anoka County Watchdog has called Petersen Coon Rapids's most conservative House member ever.
He received endorsements from North Star Tea Party Patriots Chair Walter Hudson, RNC committeewoman Pat Anderson, Rep. Peggy Scott, and Sen. Michelle Benson.
In 2013, he cosponsored a bill to legalize same-sex marriage in the state of Minnesota, which passed the Senate on May 13 with Petersen the only Republican voting for it.