Final answer:
McKinley's campaign in the 1896 election was underhanded due to the negative propaganda spread by the Republican Party.
Step-by-step explanation:
During the 1896 election, McKinley's campaign was considered underhanded because of the negative propaganda spread by the Republican Party. They spread a message that likened Populism to Communism and claimed that the Populists and their candidate, William Jennings Bryan, would destroy industry and currency if they were elected. This underhanded tactic was used to undermine Bryan's campaign and convince voters that McKinley and the Republicans were the better choice.