The 1884 election between Grover Cleveland and James Blaine was very close--Cleveland won because he carried New York (very narrowly). A few days before the election a Protestant minister, with Blaine present, had denounced the Democrats as "the party of rum, Romanism, and rebellion." Supposedly that offended enough Catholic voters in New York to tip the election to Cleveland.
After the election someone said Cleveland had defeated his opponent with the jawbone of an ass.