Why did roosevelt's republican challenger alfred landon fail in his bid for the presidency in 1936?

The failure of Alfred Landon's bid for the presidency in 1936 is often attributed to a combination of FDR's popularity, and Landon's perceived lacklustre participation in the campaign. Landon failed to participate in the Republican primaries, and was apparently unwilling to travel far afield to make campaign appearances, for which he was lampooned in contemporary media.