Robert Lewis "Rob" Cowles III (born July 31, 1950) is an American Republican politician from Green Bay, Wisconsin. He is a member of the Wisconsin Senate, representing Wisconsin's 2nd Senate district since 1987. He is the longest currently-serving member of the Wisconsin Senate, having served for 37 years. He previously served four years in the Wisconsin State Assembly (1983–1987).

Robert Cowles was born and raised and lived most of his life in Green Bay, Wisconsin. He attended the University of Wisconsin–Green Bay, earning his bachelor's degree in math and science in 1975. After graduating, he briefly pursued his master's in public administration at University of Wisconsin–Green Bay, but did not complete that degree.^[1][2][3][4]

He was formerly a director of an alternative energy division for a communications construction company.^[5]

Despite his parents being prominent local Republicans, Cowles became active in politics with the Democratic Party during his college years.^[1] In 1974, he was a campaign co-chairman for unsuccessful Democratic Wisconsin State Assembly candidate Jon A. LeDuc.^[6] During the 1976 Democratic Party presidential primaries he was an organizer in Wisconsin for Arizona U.S. representative Mo Udall's presidential campaign. He was also active in the United States Junior Chamber, and was president of the group in 1977.^[7]

In 1978, Cowles made his first bid for state elected office.^[1] He ran for Wisconsin State Assembly in what was then the 4th Assembly district; in the Democratic primary, he faced the candidate he had previously worked for, Jon A. LeDuc, who was then making his third bid for election to the Assembly. Cowles and LeDuc ran on nearly identical policy platforms, both arguing for cuts to state bureaucracy and both proposing a plan for indexing the state income tax to inflation. For Wisconsin's then-surplus, they also both advocated sending the money to municipalities in shared revenue as part of a program for municipalities to cut property taxes.^[8][9] Cowles prevailed in the primary, receiving 57% of the vote, but was defeated in the general election by Republican Gary T. Dilweg.^[10]

After losing the 1978 election, Cowles reduced his political activity and re-emerged in 1982 as a Republican. On his party-change, he explained that he found the Republican Party better fit his conservative political philosophy.^[11]

That year, he ran for Assembly again in what was then the 75th Assembly district under the 1982 court-ordered redistricting plan. He faced two opponents in the Republican primary, but prevailed with 50% of the vote. He went on to defeat Democrat Joel Edler in the general election, receiving 56% of the vote.^[12] Another redistricting act was passed in 1983, Cowles ran for his second term in 1984 in what was then the 6th Assembly district. He prevailed in another contested primary, and went on to defeat Democrat Gregory Kirschling in the general election.^[13][14]

While Cowles was being re-elected to the Assembly in 1986, his district's state senator, Don Hanaway, was being elected Attorney General of Wisconsin. Hanaway still had two years remaining on his term in the Wisconsin Senate, and therefore a special election was called for the spring of 1987 to fill the vacancy in the 2nd Senate district. Cowles was one of four Republicans who entered the special primary to succeed Hanaway, he went on to win the primary with 41% of the vote over state representative Cathy Zeuske and former representative William J. Rogers. In the general election, he defeated Democrat Rosemary Hinkfuss.^[14] Since the 1987 special election, Cowles has been re-elected nine times and survived one recall election.

In the 106th Wisconsin Legislature, Cowles chairs the Senate Committee on Natural Resources and Energy; he has been chair of the Senate committee dealing with energy legislation since 2011, and also held the chair multiple times when Republicans held the majority between 1993 and 2006.^{[note 1]} He also previously served as co-chair of the Joint Committee on Audit, and he sits on the Senate Committee on Transportation and Local Government; he has sat on the committee responsible for transportation issues since 2013.^[2][3]

Robert Cowles III is the eldest of three sons born to Robert Cowles Jr. and his wife Margaret (née Lindstrom). Robert Cowles Jr. was a mechanical engineer and a co-founder of Marathon Engineering; he was also an original shareholder in the Green Bay Packers.^[19] His father, Robert Cowles Sr., was a prominent physician and civic leader in Green Bay.^[20]

Through his paternal grandmother, Emily Cone Harris (née Murphy) Cowles, Cowles was an heir to a portion of the ownership of the Morley-Murphy Company, founded by her father, Frank Emery Murphy. Her uncle, William Herbert Murphy, was also a prominent businessman, and was one of the founders of the Lincoln Motor Company.^[21]