At the 1876 Democratic National Convention in St. Louis, Kernan nominated Samuel J. Tilden for President. In 1880, Kernan received the honorary degree of LL.D. from Georgetown University. In January 1881, Kernan was defeated for re-election by Republican Thomas C. Platt. After Platt's resignation in May 1881, Kernan ran again for the Senate in the following special election but was defeated by Republican Warner Miller. At the Democratic convention of 1884, held at Chicago, he was not a delegate, but he was present at the special request of the leaders of his party and was one of the most efficient advocates, outside of the convention, for the nomination of Grover Cleveland.