Ohio politics needed some harmony at that time. During those years, Senator Marcus A. Hanna, Senator Joseph B. Foraker, and Boss George B. Cox dominated the Republican party in the Buckeye State. When their interests coalesced, they pooled their collective majorities to achieve stunning victories. At other times they leaped at each other's throats, causing defeat through violent intraparty feuds. In this atmosphere, Warren Harding quickly became one of the best-known party pacifiers. He firmly believed that conciliation was a political weapon superior to obstruction and strife, and this fact alone made him increasingly valuable in the acrimonious environment of Ohio politics.
In 1899, Harding ran for his first elective office, the Ohio Senate, and won. He was returned in 1901 for a second term and was elected floor leader. In 1903 he was elected to the post of lieutenant governor on a ticket headed by Myron T. Herrick and for the ensuing two years served as the amiable moderator of the Ohio Senate. At the conclusion of his term as lieutenant governor, he voluntarily returned to Marion and to the Star. However, through his editorials he continued to exert considerable influence on Ohio Republican party politics.
Harding was induced to leave his "retirement" in 1910 to run as a compromise gubernatorial candidate against Judson Harmon, the Democratic incumbent. He lost, but not before making additional friends within Republican ranks because of his sensitivity to the desires of all factions. In 1912, William Howard Taft selected him to place his name in nomination at the Republican National Convention, primarily because of Harding's known conciliatory qualities. Although such soothing tactics did not prevent the Bull Moose secession, Harding returned to Ohio from the 1912 convention an even bigger political figure than when he left. Two years later, he was the party's favorite to succeed incumbent Republican Senator Theodore E. Burton and won the 1914 senatorial election by a stunning majority of one hundred thousand.
The year 1915 was not a propitious one in which to enter the United States Senate. The major legislative battles over Wilson's New Freedom program had already been fought, and fears of war were beginning to overshadow normal partisan activities. During the war itself, there was little opportunity for a junior senator to make much of a reputation, and it was not until the League of Nations question emerged in 1919 that there was an issue capable of evoking serious partisan debate.
What modest reputation Harding acquired before 1919 was secured within the fold of the party rather than on the floor of the Senate. He delivered the Republican National Convention's keynote address in 1916 and was elected its permanent chairman. His call for unity and moderation struck just the proper chord for a party still suffering from the 1912 defeat.
Meanwhile, in the Senate, he carried his committee load, shunned acrimonious debate, and generally followed the old guard—or popular opinion, if that proved more beneficial. He voted for returning the railroads to their private owners after the war and pushed for high tariffs. He was dubious about government subsidies to agriculture, opposed excess-profit taxes and high surtaxes, and took a dim view of strong executive authority. He was mildly conservative in his attitude toward unions and was not swept off his feet by the "Red Scare" of 1919–1920. On woman suffrage and Prohibition he swam with public opinion, personally being committed to neither.
On the League, Harding was generally towed along by the more influential Republican senators. But his position also rested on expediency, since he believed that his Ohio constituents opposed it. He signed Senator Lodge's "round robin" anti-League statement in March 1919 and, as a member of the powerful Foreign Relations Committee, was privy to all discussions regarding the League question. He was also one of the senatorial group that called on the White House, in mid-August 1919, to air its differences with Woodrow Wilson. In the end, Harding declared himself in favor of the Lodge reservations and voted accordingly. Although never one of the "irreconcilables," he joined with such anti-League diehards as William E. Borah, Medill McCormick, and James A. Reed at the home of Nicholas Longworth after the anti-League vote on 19 November 1919 to eat scrambled eggs and celebrate the victory.