In 1916, Johnson ran for the U.S. Senate. His popularity was still very high, and his election was considered all-but-certain. Johnson was disappointed that a conservative, Charles Evans Hughes, had won the Republican nomination for President rather than a more progressive candidate.
When Hughes campaigned in California, he was escorted by conservative political enemies of Johnson in the Republican Party. During the campaign, Johnson and Hughes stayed at the same hotel. Hughes was not aware Governor Johnson was there, and Johnson made no move to see the Presidential candidate of his party. The mutual snub was picked up in the papers. Although Hughes later sent a very gracious letter to Johnson, it didn't help. Word went through the progressive faction of the party to support Johnson for the Senate, but Democrat Woodrow Wilson for President. Johnson won his Senate race by more than 300,000, but Hughes lost California by four thousand votes. Losing California cost Hughes the election. Had Hughes carried California, he would have been President. There is no doubt that with the support of Johnson, Hughes would have taken California and the White House.
New York Congressman John Dwight later said Hughes could have won the election with a single dollar. He said that Hughes could have carried the state and the election if "a man of sense, with a dollar, would have invited Hughes and Johnson to his hotel room when they were both in the same hotel in California. He could have ordered three Scotch whiskies, which would have been seventy-five cents, and that would have left a tip of twenty-five cents for the waiter...That little Scotch would have brought those men together; there would have been mutual understanding and respect and Hughes would have carried California and been elected."
In the Senate, Johnson became immediately identified with the staunch isolationists. He only reluctantly agreed to vote for American entry into World War I, and regretted the decision later. He fought against the Versailles Treaty and U.S. membership in the League of Nations. When President Wilson went on his cross-country trip to campaign for the League of Nations, Johnson was one of the Senators who followed, campaigning against the League.
