A member of the Republican Party of Minnesota, he represented District 54B, which included portions of Dakota and Washington counties in the southeastern part of the Twin Cities metropolitan area.
McNamara attended Archbishop Brady High School in West Saint Paul, then went on to the University of Minnesota in Duluth for two years.
He graduated from the Carlson School of Business at the University of Minnesota in Minneapolis in 1976, earning his B.S.
On November 27, 2017, McNamara announced he would run in the special election for the Minnesota Senate seat vacated by Dan Schoen.
He lost the election to former DFL State Representative Karla Bigham and Libertarian candidate Emily Mellingen.