Although many candidates sought the Republican nomination, only two, Governor Landon and Senator Borah, were considered to be serious candidates. While favorite sons County Attorney Earl Warren of California, GovernorWarren E. Green of South Dakota, and Stephen A. Day of Ohio won their respective primaries, the 70-year-old Borah, a well-known progressive and "insurgent," carried the Wisconsin, Nebraska, Pennsylvania, West Virginia, and Oregon primaries, while also performing quite strongly in Knox's Illinois and Green's South Dakota. However, the party machinery almost uniformly backed Landon, a wealthy businessman and centrist, who won primaries in Massachusetts and New Jersey and dominated in the caucuses and at state party conventions.
With Knox's candidacy withdrawing in order to become Landon's selection for Vice President, and Day, Green, and Warren releasing their delegates, Landon's victory was assured.