In 1938, Chandler, still in office as governor, opposed the re-nomination of U.S. Senator [[Alben Barkley|Alben William Barkley]], a [[New Deal]]er and favorite of President [[Franklin D. Roosevelt]], who came into the commonwealth to campaign for Barkley. Chandler lost the primary race to Barkley.<ref>[https://www.ourcampaigns.com/RaceDetail.html?RaceID=491885 KY US Senate - D Primary Race - Aug 06, 1938]. ''Our Campaigns''. Retrieved July 31, 2021.</ref> The following year, Kentucky's other Democratic senator, Marvel Mills Logan (1874–1939) of Elizabethtown, died in office, and Chandler resigned as governor so that his successor, Keen Johnson (1896–1970), could appoint him to the vacant Senate seat.<ref>[https://bioguideretro.congress.gov/Home/MemberDetails?memIndex=C000290 Biographical Directory of the U.S. Congress - Retro Member details], accessed July 31, 2021.</ref>
In 1945, Chandler left the Senate to succeed Kenesaw Mountain Landis (1866–1944), a [[Segregation|segregationist]], as commissioner of baseball. In this capacity, Chandler approved the contract of [[Jackie Robinson]] with the former [[Brooklyn Dodgers]] and hence [[Segregation|desegregated]] baseball. The baseball owners had all opposed admitting Robinson into the league, but Chandler overruled them. Chandler established the first pension fund for MLB players financed by [[radio]] rights on the [[World Series]]. The baseball owners, influenced by Dodgers manager Leo Ernest Dorocher (1905–1991), whom Chandler derided for alleged times to [[gambling]], did not renew his contract in 1951.<ref>[https://baseballhall.org/hall-of-famers/chandler-happy Chandler, Happy | Baseball Hall of Fame], accessed July 31, 2021.</ref><ref name=utube/>
Following his term as commissioner, Chandler returned to Kentucky and won a second term as governor in 1955. He presided over the racial integration of state schools and established a medical school at the [[University of Kentucky]], renamed the Chandler Medical Center. Following his second term as governor, his political influence began to wane as he made three more unsuccessful runs for governor in 1963, 1967 (when the Republican [[Louie B. Nunn|Louie Broady Nunn]] was elected), and 1971, when the office passed to the Democrat Wendell Hampton Ford (1924–2018), later one of the state's two U.S. senators.
Chandler's support in 1987 for dark-horse gubernatorial candidate Wallace Glenn Wilkinson (1941–2002) paid off as Wilkinson resisted calls to remove Chandler from the University of Kentucky board of trustees following the former governor's use of a racial expression at a 1988 board meeting. Chandler was first appointed to the trustess by Louie Nunn, whom Chandler supported In the 1967 election. In 1968, he was considered as a vice-presidential running mate for [[Alabama]]'s [[George Wallace]] third-party campaign,<ref>Gore, Leada (August 21, 2018). [https://www.al.com/news/erry-2018/08/937bc749e09952/george-wallace-1968-presidenti.html George Wallace 1968 presidential run: 'Most influential loser' in political history]. ''al.com''. Retrieved July 31, 2021.</ref> but the two could not resolve their "racial differences";<ref>Andy Mead and Jim Warren, "Kentucky's "Happy" Chandler Dies, ''Lexington Herald-Leader,'' June 16, 1991, p. A-1.</ref> in contrast to Wallace's racist and demagogic rhetoric, Chandler held a mixed record on [[civil rights]] throughout his career.<ref>Hill, John Paul (December 2009). [https://athenaeum.libs.uga.edu/handle/10724/26071 A.B. "Happy" Chandler and the politics of civil rights]. ''University of Georgia''. Retrieved July 31, 2021.</ref>