Having originally been elected as a member of the Republican Party in 1990,[3] Rothhaus joined the Libertarian Party in 1991.[4] The next year he was re-elected as a Libertarian.[5] He went on to serve on the Merrimack selectboard from 1995 until 2001.[2] In 2001 he unsuccessfully ran for a seat on the Merrimack school board.[1] In October 2003 he was sworn in for a six-month term as a member of Merrimack's ethics committee.[6] In May 2015 he endorsed Rand Paul's 2016 presidential campaign.[7] As of 2017 he is a member of the Merrimack Town Council, serving a three-year term that will expire in 2020.[8][9]