Question: During Maine gubernatorial election, 1956, which candidate ran, who later on ran for Vice President of the United States?

Context articles: Edmund Muskie
Mississippi gubernatorial election, 1935
Mississippi gubernatorial election, 1943
Mississippi gubernatorial election, 1951
Mississippi gubernatorial election, 1923
Mississippi gubernatorial election, 1927
Mississippi gubernatorial election, 1939
Mississippi gubernatorial election, 1931
Maine gubernatorial election, 1952
Maine gubernatorial election, 1956

Edmund Sixtus "Ed" Muskie ( ; March 28, 1914March 26, 1996) was an American statesman who was the 58th United States Secretary of State under President Jimmy Carter, a U.S. Senator from Maine from 1959 to 1980, the 64th Governor of Maine from 1955 to 1959, a member of the Maine House of Representatives from 1946 to 1951, and the Democratic Party's nominee for Vice President of the United States in the 1968 election.
The 1935 Mississippi gubernatorial election took place on November 5, 1935, in order to elect the Governor of Mississippi.
 Incumbent Democrat Martin S. Conner was term-limited, and could not run for reelection to a second term.
 As was common at the time, the Democratic candidate ran unopposed in the general election so therefore the Democratic primary was the real contest, and winning the primary was considered tantamount to election.
The 1943 Mississippi gubernatorial election took place on November 2, 1943, in order to elect the Governor of Mississippi.
 Incumbent Democrat Paul B. Johnson Sr. was term-limited, and could not run for reelection to a second term (he died less than two months after the election was held).
 As was common at the time, the Democratic candidate ran unopposed in the general election so therefore the Democratic primary was the real contest, and winning the primary was considered tantamount to election.
The 1951 Mississippi gubernatorial election took place on November 6, 1951, in order to elect the Governor of Mississippi.
 Incumbent Democrat Fielding L. Wright was term-limited, and could not run for reelection to a second full term.
 As was common at the time, the Democratic candidate ran unopposed in the general election so therefore the Democratic primary was the real contest, and winning the primary was considered tantamount to election.
The 1923 Mississippi gubernatorial election took place on November 6, 1923, in order to elect the Governor of Mississippi.
 Incumbent Democrat Lee M. Russell was term-limited, and could not run for reelection to a second term.
 As was common at the time, the Democratic candidate ran unopposed in the general election so therefore the Democratic primary was the real contest, and winning the primary was considered tantamount to election.
The 1927 Mississippi gubernatorial election took place on November 8, 1927, in order to elect the Governor of Mississippi.
 Incumbent Democrat Dennis Murphree, as he had not served a full term, was eligible for and ran for election.
 As was common at the time, the Democratic candidate ran unopposed in the general election so therefore the Democratic primary was the real contest, and winning the primary was considered tantamount to election.
The 1939 Mississippi gubernatorial election took place on November 7, 1939, in order to elect the Governor of Mississippi.
 Incumbent Democrat Hugh L. White was term-limited, and could not run for reelection to a second term.
 As was common at the time, the Democratic candidate ran unopposed in the general election so therefore the Democratic primary was the real contest, and winning the primary was considered tantamount to election.
The 1931 Mississippi gubernatorial election took place on November 3, 1931, in order to elect the Governor of Mississippi.
 Incumbent Democrat Theodore G. Bilbo was term-limited, and could not run for reelection to a second term.
 As was common at the time, the Democratic candidate ran unopposed in the general election so therefore the Democratic primary was the real contest, and winning the primary was considered tantamount to election.
The 1952 Maine gubernatorial election took place on September 8, 1952.
 Incumbent Republican Governor Frederick G. Payne was term limited and seeking election to the United States Senate, thus did not run.
 Maine Senate President Burton M. Cross faced off against Democratic challenger, former Congressman James C. Oliver (who served in Congress as a Republican) and Independent Neil Bishop in the general election, easily defeating both men.
 Burton's election was the ninth consecutive victory for the Republicans in Maine gubernatorial races.
The 1956 Maine gubernatorial election took place on September 10, 1956.
 Incumbent Democratic Governor Edmund Muskie was seeking re-election, and faced off against Republican Willis A. Trafton, Jr. in the general election.
 Extremely popular, Muskie was able to easily win re-election.