Former President Theodore Roosevelt challenged William Howard Taft for the Republican nomination, dissatisfied with his successor's policies and encouraged by a groundswell of popular support.

Despite this support, Roosevelt was unable to crack Taft's hold over the convention and caucus systems by which most delegates were selected and, declaring the nomination illegitimate, broke off to form the Progressive Party.

With the Republicans split between Roosevelt and Taft, Democratic nominee Woodrow Wilson easily won a landslide election, albeit with a plurality of the vote.

The 1914 midterm elections were a disappointment for the Republicans; the Democratic Party retained control of both chambers for the first time since the American Civil War.

Within the Republican Party, views of the war were mixed: After the sinking of the RMS Lusitania in May 1915, American public opinion turned decisively in favor of the Allied forces.

Entering the 1916 election, Republicans were aware that the greatest threat to victory was the continued opposition of the Progressive Party, and in particular Theodore Roosevelt, who remained immensely popular.

Much of his time was devoted to defending a libel suit brought by William Barnes Jr.[11] In January 1916, Republicans and Progressives negotiated the possibility of fusion in the upcoming election.

Nearly all of the Northern United States permitted a public vote on the presidential nomination, with Iowa, Indiana, Michigan, Minnesota, New Hampshire, Montana, West Virginia adopting the practice between 1912 and 1916.

Nevertheless, the entire South, most of the Rocky Mountain states, and Maine, Connecticut, Rhode Island, and Washington maintained the use of closed delegate conventions or caucuses, which tended to favor conservatives.

Early in the campaign, Theodore Roosevelt attempted to dampen widespread hopes that he would accept a joint Republican and Progressive nomination.

Hughes, as Associate Justice of the Supreme Court, had the virtue of making few statements on political issues; even as an active politician, he had a character for reticence.

"[62] Sufficiently flattered, Hughes consulted with his colleagues Willis Van Devanter and Edward Douglass White; both urged him to accept if nominated.

Hughes responded that he would not allow the offer to affect his decision; he may have resolved to accept the nomination rather than be implicated in an apparent quid pro quo with Wilson.

The Progressives made clear that the only acceptable name was Roosevelt; Republicans balked and resolved to risk a split by nominating Hughes or a more conservative man.