John Randolph Thune (born January 7, 1961) is an American politician and senior United States Senator from South Dakota, a member of the Republican Party.
 He previously served as a United States Representative for South Dakota 's at-large congressional  .
 He became South Dakota's senior senator with the retirement of Tim Johnson in 2015.
 He is South Dakota's senior senator, having served as the GOP's Chief Deputy Whip in 2006, chairman of the Republican Policy Committee in June 2009, and Republican Conference Chairman in 2011, the third-ranking position in the Senate.
 He has worked in politics and civic organizations since completing his MBA graduate degree.
 He is also the current dean of South Dakota's congressional delegation.
George McGovern, a Democratic Party politician from South Dakota, was first elected to the United States House of Representatives to represent South Dakota's 1st congressional district in 1956.
 He was re-elected in 1958, before making an unsuccessful run for the United States Senate in 1960 against Republican incumbent Karl Earl Mundt.
 After serving in the John F. Kennedy administration as director of the Food for Peace program, McGovern ran again for the Senate and narrowly prevailed over appointed Senator Joseph H. Bottum.
 In 1968, McGovern unsuccessfully sought the Democratic Party's presidential nomination at the Democratic National Convention and was re-elected to the Senate over former Governor of South Dakota Archie M. Gubbrud.
 In 1972, McGovern was successful in his campaign for the Democratic presidential nomination, but lost the election in a landslide to incumbent President Richard Nixon.
 McGovern was re-elected to the Senate in 1974 over Vietnam War veteran Leo K. Thorsness, but lost re-election in 1980 to then-U.S. Representative James Abdnor.
 McGovern made a final unsuccessful run for president in United States presidential election, 1984.
John Henry Hoeven III (born March 13, 1957) is an American politician and the senior United States Senator from North Dakota, in office since 2011.
 A member of the North Dakota Republican Party, he previously served as the 31st Governor of North Dakota from December 2000 to December 2010.
 Hoeven was elected to the U.S. Senate in the November 2, 2010 general election.
 He replaced junior Senator Byron L. Dorgan, who chose not to seek re-election.
 Hoeven became the senior Senator in 2013 after Kent Conrad retired and was replaced by Heidi Heitkamp, who was once Hoeven's opponent for the Governor's office.
Kat Swift (born June 6, 1973) is a United States political activist, former co-chair of the Green Party of Texas, and spokesperson for the Green Party's National Women’s Caucus.
 Swift announced her intention to seek the 2008 Presidential nomination of the US Green Party at the 2004 Green Party National Convention in Milwaukee, Wisconsin.
 She was one of the youngest candidates to seek the office in 2008, meeting the age requirement of 35-years-old only months before Election Day in 2008.
 In 2007, she ran for City Council, District 1 in San Antonio, Texas finishing second of three candidates with 1,630 votes for 29.48% of the total vote.
 On July 12, 2008 she finished third on the single ballot for the party's presidential nomination with 38 out of 532 delegate votes cast.
 She later endorsed the winner of the presidential nomination Cynthia McKinney.
 Swift was later a 2010 candidate for Bexar County Commissioner in Precinct 2.
Samuel Dale Brownback (born September 12, 1956) is an American politician and diplomat who is the 46th Governor of Kansas.
 A member of the Republican Party, Brownback was first elected to the U.S. House of Representatives during the Republican Revolution of 1994, representing Kansas's 2nd congressional district for a single term, before running in a 1996 special election for the U.S. Senate seat previously held by Bob Dole.
 He won the special election and the following two regular elections, serving until 2011.
 He ran for president in 2008, but withdrew before the primaries began and endorsed eventual Republican nominee John McCain.
 He was elected Governor of Kansas in 2010 and took office in January 2011.
William Thad Cochran (born December 7, 1937) is an American Republican politician.
 He is the current senior United States Senator from Mississippi (the third most-senior Senator and the second most-senior Republican member), first elected to the Senate in 1978, and the Chairman of the Senate Appropriations Committee, which he had also chaired from 2005 to 2007.
 He also chaired the Senate Agriculture Committee from 2003 to 2005.
 Cochran won reelection to a seventh term in 2014, after defeating Chris McDaniel in an intense primary run-off election.
 He is currently the dean of the Mississippi congressional delegation.
 He is also on track to become the longest serving Republican Member of Congress if he serves until 2019, surpassing Joseph Gurney Cannon, former Speaker of the House, who served for 46 years.
John Sidney McCain III (born August 29, 1936) is an American politician who currently serves as the senior United States Senator from Arizona, in that office since 1987.
 He was the Republican nominee for President of the United States in the 2008 election, which he lost to Barack Obama.
Electoral history of Mike Gravel, Speaker of the Alaska House of Representatives (1965–1966), United States Senator from Alaska (1969–1981), candidate for the 1972 Democratic Party Vice Presidential nomination and 2008 Democratic and later Libertarian Presidential nomination
Patrick Joseph Leahy (born March 31, 1940) is an American politician and the senior United States Senator from Vermont, since 1975.
 A member of the Democratic Party, Leahy served as the President pro tempore of the United States Senate from December 17, 2012, to January 6, 2015.
 As President pro tempore, he was third in the presidential line of succession.
 He is the most senior senator and took office at 34 years old, younger than any other current senator.
 Leahy received the title of President pro tempore emeritus upon the commencement of the 114th Congress.
 He is the last remaining member of the Senate to have served prior to the 1976 election of President Jimmy Carter.
Electoral history of Christopher Dodd, senior United States Senator from Connecticut (1981-2011), United States Representative (1975–1981), Democratic National Committee Chairman (1995–1997) and a candidate for the 2008 Democratic Presidential nomination

Question: Which governor of Kansas endorsed the presidential nomination of a current senior United States Senator from Arizona?
Answer: Samuel Dale Brownback