Ronald Wilson Reagan (February 6, 1911 – June 5, 2004) was the 40th President of the United States and the 33rd Governor of California. Born in Tampico, Illinois, Reagan moved to Los Angeles in 1937. He began a career as an actor, first in films and later television, appearing in 52 movie productions and gaining enough success to become a household name. Though largely a B-film actor, some of his most notable roles are in Knute Rockne, All American and Kings Row. Reagan served as president of the Screen Actors Guild, and later spokesman for General Electric; his start in politics occurred during his work for GE. Originally a member of the Democratic Party, he switched to the Republican Party in 1962. After delivering a rousing speech in support of Barry Goldwater's presidential candidacy in 1964, he was persuaded to seek the California governorship, winning two years later and again in 1970. He was defeated in his first run for the Republican presidential nomination, but won both the nomination and election in either 1978 or 1980.
The season 5 episode 7A WF 83429 mentions the 1986 bombing of Libya that happened during his administration, but doesn't specify which president ordered the raid. The Newman administration occurred in 1987-1991, placing Reagan's in either 1979-1987 (after the point of divergence in the presidential election cycle) or in 1981-1987 (with the divergence taking place during Reagan's second term, possibly due to illness).
Reagan real-life re-election bid in 1984 may have been one of the campaigns Bruno was referring to, when he was being interviewed for the Vinick Campaign, as one of the Republican nominees who managed to win 49 states "in the last 30 years" (the other presumably being Richard Nixon in 1972, which more precisely occurred 34 years before). However, it may also refer to Owen Lassiter's re-election in 1994, in which he presumably won every state but Massachusetts. The TV series does not explicitly acknowledge much that happened during either administration, however.
It is notable that Lassiter shares many characteristics with Reagan; both were conservative Republicans with two-term administrations (though originally Democrats) of rather high age (in their 70s upon retirement). Both previously served as Governor of California before being narrowly defeated for the Republican nomination by a more moderate candidate who was eventually defeated (Joseph Furman and Gerald Ford) but won the next election? by successfully defeating a liberal Democratic incumbent from the Deep South (D.W. Newman and Jimmy Carter, respectively). As mentioned, both presumably won re-election over that President's Vice President, coming first in every state but his opponent's home state (Massachusetts for Roland Pierce, Minnesota for Walter Mondale).