I always found it curious that in Advise and Consent, as well as the novels that followed it, all the larger political differences -- liberal/conservative, hawk/dove -- were played out within the so-called "majority party." The "minority party" seemed to be there only as a formality, a token from which we never heard much.
shareI thought it was because the Democrats were more like that in those days. They nominated HST in 1948, a very anti-communist hawk (though more liberal on social matters) yet Stevenson in 1952, a liberal dove who ran in opposition to the war HST intervened in.
The Democrats then nominated JFK in 1960 on a hawkish foriegn policy platform and while liberal on some social matters, on fiscal matters he called for tax cuts (marginalk rates under Eisenhower reached 90%). It is forgotten today but JFK ran to the right of Nixon on foreign policy. Eisenhower was content to sit back figuring the Soviets would eventually collapse. He threatened "massive retaliation" should the Soviets invade Western Europe. He wanted the US to be militarly strong, but figured for the most part the Soviet Union would eventually collapse.
JFK was elected arguing for a more robust and aggressive foreign policy based in part on a non existant missile gap. As president he theratened to invade Cuba and overthrew the South Vietnamese government for not fighting the Viet Cong better (one conspiracy theory was that JFK's assassination was by supporters of assasinated South Vietnam President Diem).
So at the time, it seemed quite possible the battle lines within the Democratic Party would have been drawn as shown in the movie.