He got caught up in an immigration scandal

Just a few weeks before the general election for president in November 1880, Garfield's political rivals attempted to endanger his campaign by disseminating a letter he had written to an acquaintance called H.L. Morey about the issue of foreign labor. In it, Garfield advocated for Chinese laborers, a contentious stance at a time when the nation was concerned about how immigration may influence employment. Democrats distributed tens of thousands of copies of the letter to discourage people from supporting him. The possibility of hiring immigrant labor ignited a riot in Denver.

Garfield initially kept quiet, but not because he was embarrassed by the letter. It was dated shortly after he was elected to the Senate, and he had signed many letters that he and his friends had sent in response to the congratulations messages he had received. He just couldn't recollect writing or signing it. However, after talking to his pals, he issued a denial. Later, after seeing a copy of it in a newspaper, Garfield declared it to be a fake. The term "H.L. Morey" didn't appear to exist, either. It turns out that the letter was planted by the adversary to tarnish Garfield's reputation. The letter's publisher, journalist Kenward Philp, was accused of fabrication and libel but was found not guilty. One witness who stated they had met Morey was sentenced to eight years in prison for lying.