Increased support for suffrage there and among Senate Republicans meant that by the time Congress voted on the issue, Harding was a firm supporter. Harding, who drank,[60] initially voted against banning alcohol. He voted for the Eighteenth Amendment, which imposed prohibition, after successfully moving to modify it by placing a time limit on ratification, which was expected to kill it. Once it was ratified anyway, Harding voted to override Wilson's veto of the Volstead Bill, which implemented the amendment, assuring the support of the Anti-Saloon League.[61]
Harding, as a politician respected by both Republicans and Progressives, was asked to be temporary chairman of the 1916 Republican National Convention and to deliver the keynote address. He urged delegates to stand as a united party. The convention nominated Justice Charles Evans Hughes.[62] Harding reached out to Roosevelt once the former president declined the 1916 Progressive nomination, a refusal that effectively scuttled that party. In the November 1916 presidential election, despite increasing Republican unity, Hughes was narrowly defeated by Wilson.[63]
Harding spoke and voted in favor of the resolution of war requested by Wilson in April 1917 that plunged the United States into World War I.