Argus Leader political columnist David Montgomery described Rapid City as an overwhelmingly Republican town where local politics is hotly contested between factions within the Republican Party which Montgomery designates as the "Establishment Party" and the "Outsider Party." Kooiker was named to the Rapid City Planning Commission by then-mayor Jerry Munson in 2001, and served until 2002. He was elected to the Rapid City Common Council later that year and represented Ward 2 until he was elected mayor. While serving on the council, he was censured publicly in 2010. The 2010 censure was the first public rebuke of an elected official in Rapid City history. Kooiker had defeated
Alan Hanks and incumbent
Jim Shaw in the first mayoral election of 2007, but a runoff three weeks later was won by Hanks. The next year, Kooiker applied for the position of city administrator in
Cherokee, Iowa, but did not get the job, which instead went to Don Eikmeier. and was elected mayor that year by "a wave of overwhelming support in some of the city's poorer precincts," defeating Hanks by 478 votes. Kooiker took office on July 5, 2011. He ran for reelection in 2013, against
state senator Mark Kirkeby. Kooiker defeated Kirkeby, by 4,702 votes. In 2014, Kooiker appointed Lt. Elias Diaz, an officer of Native American and Hispanic heritage, as chief of police. When the appointment met with opposition in the city council, Kooiker appointed Karl Jegaris instead. Kooiker lost his bid for a third term in June 2015, as former Rapid City police chief Steve Allender won the election by 1,226 votes. Kooiker's second mayoral term ended on July 6, 2015.
Cherokee, Iowa mayor Mark Murphy announced Kooiker's hiring as city administrator in October 2015. Kooiker was sworn in on December 22, 2015, though he had begun work earlier that month. In 2017, governor
Kim Reynolds named Kooiker to the
Iowa Civil Rights Commission. Kooiker was offered the
city manager position in Sheldon, Iowa, in October 2018. Sheldon's city council voted to approve the hiring of Kooiker later that month, and he assumed the office in December 2018, == Personal ==