Rockefeller was the only other major potential candidate and even he backed out after seeing just how well Nixon controlled the Republican Party of the time.
Although if you just want Republicans to win, Nixon beating JFK is reasonable.
True but we always talk about the same three candidates for the GOP in 1960...Goldwater for the Conservative Wing, Rocky for the Moderate wing and Nixon as the in between. But what about some other potential candidates that could run for Ike's third term.
1. Secretary of Labor James P. Mitchell of New Jersey: Largely hailed as the "Conscience" of the Republican Party, He was one of the Eisenhower 10, former Democrat and a fighter for Civil Rights in the Work place. With his close relationship with Eisenhower, Mitchell wouldn't have a problem sowing up the Eastern GOP Establishment but he might have a few issues with the growing wing of Western Conservatives.
2. Governor George D. Clyde of Utah: A popular Western Governor, with strong fiscally conservative credentials during his tenure. However, he does come from a traditional GOP Stronghold, that really wouldn't add anything to the Electoral Math. He might make a good Vice Presidential pick though.
3. Senator John S. Cooper of Kentucky: Classic Moderate-to-Liberal Republican yet from the Upper South, which may allow for him to pick crucial border states like Missouri, Tennesse, and Virginia. He also fastly approached the 14 years mark, being in the senate since 1946. Cooper's Anti-McCarthyisim, Pro-Civil Rights, Anti-Vietnam, and history of Dipolomatic expierence would make for an interesting 1960's.
4. Governor Cecil H. Underwood of West Virgina: Probably the only candidate whose appeal to the youth would rival Kennedy's. Governor of a crucial swing state(Especially one that was a make or break state for Jack in the Primaries), the 38 year old GOP Boy Wonder's record of Civil Service reform, push for Retirment Pension's, Evangelical background, and Pro-Civil Rights stance would make him a fine nominee. However it does seem that he had trouble winning elections, being defeated twice in the '60's.