The 1946 United States Senate election in Montana took place on November 5, 1946.
 Incumbent United States Senator Burton K. Wheeler, who was first elected to the Senate in 1922, and was re-elected in 1928, 1934, and 1940, ran for re-election.
 He was challenged in the Democratic primary by Leif Erickson, the Chief Justice of the Montana Supreme Court, and, following a close election, was narrowly defeated by Erickson.
 In the general election, Erickson faced State Senator Zales Ecton, the Republican nominee.
 Ultimately, Ecton defeated Erickson by a fairly wide margin, and won his first and only term in the Senate.
Peter Donald Shack (born 20 June 1953) is a former Australian politician.
 Born in Perth, Western Australia, he was educated at Wesley College, Perth and the University of Western Australia before becoming a company director and political advisor.
 In 1977, he was elected to the Australian House of Representatives as the Liberal member for Tangney.
 He was defeated by Labor's George Gear in 1983.
 However, a redistribution for the 1984 election made Tangney notionally Liberal, forcing Gear to transfer to nearby Canning.
 Shack ran for his old seat in that election and won it with a large swing.
 He held the seat without serious difficulty until his retirement in 1993.
Debra Strobel Fischer (born March 1, 1951) is the senior United States Senator from the state of Nebraska.
 Previously, she was a two-term member of the Nebraska Legislature, representing the 43rd District.
 She defeated former United States Senator Bob Kerrey in the election held on November 6, 2012, and assumed one of Nebraska's two Senate seats in January 2013.
Kathleen Joan "Kath" Venn {'1': ", '2': ", '3': ", '4': "} (born 12 November 1926) is a former Australian politician.
 Born in Tasmania, she was a Labor member of the Tasmanian Legislative Council from 1976 to 1982, representing the seat of Hobart.
 In 1982, she was defeated.
 She ran for the Senate in the 1984 election as an independent affiliated with Senator Brian Harradine, and received 8.6% of the vote, but preferences from Labor and the Nuclear Disarmament Party gave the seventh seat to Democrat Norm Sanders, who had 6% of the vote.
The 1942 United States Senate election in Montana took place on November 3, 1942.
 Incumbent United States Senator James E. Murray, who was first elected to the Senate in a special election in 1934 and was re-elected in 1936, ran for re-election.
 Following his victory in a competitive Democratic primary, Murray advanced to the general election, where he was opposed by former United States Attorney for the District of Montana Wellington D. Rankin, the Republican nominee and brother of representative Jeannette Rankin.
 In a closely fought election, Murray narrowly defeated Rankin to win re-election to his third term and his second full term in the Senate.
Rudolph Ely "Rudy" Boschwitz (born November 7, 1930) is a former Independent-Republican United States Senator from Minnesota.
 He served in the Senate from December 1978 to January 1991, in the 96th, 97th, 98th, 99th, 100th, and 101st congresses.
 He was then defeated by Paul Wellstone.
The 1960 United States Senate election in Montana took place on November 8, 1960.
 Incumbent United States Senator James E. Murray, who was first elected to the Senate in a special election in 1934 and was re-elected in 1936, 1942, and 1948, and 1954, declined to seek re-election, creating an open seat.
 United States Congressman Lee Metcalf won out in a crowded Democratic primary and faced off against former United States Congressman Orvin B. Fjare, who won in a similarly-crowded Republican primary.
 Following a close general election, Metcalf narrowly defeated Fjare to win his first term in the Senate.
Theodore Adams "Ted" Mondale (born October 12, 1957) is a politician, entrepreneur, public administrator, and former Chief Executive Officer of the Minnesota Sports Facilities Authority, which oversaw Minnesota Vikings stadium from conception to operation.
 He is the elder son of the former United States senator, United States ambassador and Vice President Walter Mondale and Joan Mondale.
 He is a former Minnesota state senator, former Chairman of the Metropolitan Council, 1999-2003 , and former CEO of Nazca Solutions, Inc. - a technology fulfillment venture based in Minneapolis, Minnesota.
The 1984 United States Senate election in Minnesota was held on November 6, 1984.
 Incumbent Republican U.S. Senator Rudy Boschwitz defeated Democratic challenger Joan Growe.
The 2004 United States Senate election in Iowa was held on November 2, 2004.
 Incumbent Republican United States Senator Chuck Grassley ran for re-election to a fifth term in the United States Senate.
 Grassley and former State Senator Arthur A. Small won the Republican and Democratic primaries, respectively, unopposed, and faced each other in the general election.
 Though this election coincided with the highly competitive presidential election, Grassley was in little danger of losing his seat and defeated Small handily.

Question: A former Independent-Republican United States Senator from Minnesota defeated who in the 1984 election?
Answer: Joan Growe