JFK got 43% of the Protestant vote, which was slightly BETTER than the Democrats had done in a few elections. With no JFK there would have not Kennedy empire or Johnson, or Vietnam, or the 1960s, it was the election which destroyed us.
However, if there is one man who can take the most credit for the 1965 act, it is John F. Kennedy. Kennedy seems to have inherited the resentment his father Joseph felt as an outsider in Bostons WASP aristocracy. He voted against the McCarran-Walter Act of 1952, and supported various refugee acts throughout the 1950s. In 1958 he wrote a book, A Nation of Immigrants, which attacked the quota system as illogical and without purpose, and the book served as Kennedys blueprint for immigration reform after he became president in 1960. In the summer of 1963, Kennedy sent Congress a proposal calling for the elimination of the national origins quota system. He wanted immigrants admitted on the basis of family reunification and needed skills, without regard to national origin. After his assassination in November, his brother Robert took up the cause of immigration reform, calling it JFKs legacy. In the forward to a revised edition of A Nation of Immigrants, issued in 1964 to gain support for the new law, he wrote, I know of no cause which President Kennedy championed more warmly than the improvement of our immigration policies. Sold as a memorial to JFK, there was very little opposition to what became known as the Immigration Act of 1965.
Lyndon Johnson had his own reasons for breaking the dam on Mexican immigration, and he'd been at it since the early 1950's, when Pres. Eisenhower overcame LBJ's interference in the termination of the WW II bracero labor program (and repatriation of the overstaying Mexican nationals) by writing an Executive Order deporting the braceros.
Johnson's motive was to import a huge new solid-Democrat voting bloc who would nullify the Dixiecrats, Southern white Democrats who were being progressively alienated from the Democratic Party by its adhesion to the 90%-solid, straight-ticket bloc voting of urban Negroes, and its program to register millions of blacks across the South to the same end through the Voting Rights Act of 1965.
When he signed the Voting Rights Act, Johnson commented that he and the Democrats had just given up the White House for the next 20 years. The Immigration Act was to be his, and Ted Kennedy's, counter.
With no Sam "Momo" Giancana to vote the Chicago graveyards, there'd have been no JFK.
With no homosexual J. Edgar Hoover in the Mob's pocket, there'd have been no Sam Giancana, or at least nobody with enough corrupt swing to steal the election.
It all flows downhill from that one fact.