This is based on a scenario proposed by Electric Monk
here.
39th President of the United States: Ronald Reagan, Democrat
1973-1981
Wining a seat in House of Representatives in 1952 confirms Reagan's Liberalism (whereas becoming a spokesman for GE OTL confirmed his conservatism). In 1958, Reagan won a seat in the Senate, known for his defense of liberal social policy, specifically opposing the Eisenhower administration's lack of support for municipal rail projects as they expanded highways and for proposing radical education reform.
In 1960, Richard Nixon beat John F. Kennedy. Krushchev does not put missiles in Cuba nor does the US get involved in Vietnam. Nixon passes a Civil Rights Act, mostly via a parliamentary trickiness. Backlash by moderate Republicans leads to the narrow victory of JFK, back for a rematch in 1964. However, JFK's championing of the 1966 Voting Rights Act and the multiple scandals that erupted concerning his personal life derailed his Presidency, as well as the planned social reforms he championed. In California, Senator Reagan won the Governorship in 1966. In 1968, Henry Cabot Lodge defeated JFK and George Wallace to become president. He begins an early Detente with the USSR and presides over increasing racial tensions and social despair.
Hence, in 1972 Ronald Reagan electrified the nation and the Democratic party with the so-called "Reagan Revolution." Reasserting the spirit of FDR and Harry Truman, Reagan insisted that Government should and would be a force for good in American society. However, he radically changed the nature of social welfare in the US. The introduction of school choice, abolishing local property taxes in favor of federally funded vouchers for all public schools, provided a mechanism to address inequality both of income and race, and avoided the demographic fallout of briefly proposed "busing" fiascoes. In 1974, he issued the "New Energy Society", creating the EPA, instituting high performance standards on the automotive industry, and providing federal funding for High Speed Rail throughout the United States. His crowning achievements came, nonetheless, in his second term with the passage of the Negative Income Tax (which replaced all prior forms of welfare) and the "Equal Opportunity Act of 1976" which mandated affirmative action on the basis of economic background. With the election of his Vice-President, John Connally to office in 1980, the rebirth of American Liberalism--the legacy of Ronald Reagan--was confirmed.