In 1848 he was elected to the United States House of Representatives to fill a vacancy for three months. With great vigor he charged upon several of the most prominent abuses of the time, and selecting the practice of paying mileage to Congressmen, he assaulted that with a vehemence which ultimately destroyed it. As a member of Congress he also introduced the first bill to give free homesteads to actual settlers on the public lands. He was a candidate in 1861 for United States Senator, but was defeated by Ira Harris, of Albany. In 1864 he was one of the Republican Presidential Electors, and in 1870 was nominated for Congress in a hopelessly Democratic district, and was defeated. He had always been an intense opponent of human slavery, and in 1848 his hostility to the war with Mexico was doubtless inspired by his dread of the extension of the slave system. He was an enthusiastic supporter of John C. Fremont, who was nominated for President by the Republicans in 1856; and he made his newspaper so dreaded and feared by the opposition that he was indicted in Virginia for circulating incendiary documents through its columns. During these years he was an incessant and untiring worker, and produced for the columns of his own and other newspapers a prodigious amount of matter. He had heretofore labored in politics in conjunction with William H. Seward, Governor, and afterward United States Senator. In 1854 the separation between Greeley, Seward, and Thurlow Weed became established, and Mr. Seward's friends prevented the election of Mr. Greeley as a delegate to the Republican Convention which nominated Abraham Lincoln in 1860. Greeley, however, obtained a seat as delegate in the Convention as a representative from the State of Oregon, and in that capacity he, more than any other man, doubtless turned the tide against Mr. Seward and in favor of Abraham Lincoln, who was nominated by the Convention. At the breaking out of the Civil War Mr. Greeley manifested great trepidation and reluctance to face the issue. He even advised in _The Tribune_ that the "Erring Sisters" be allowed to depart in peace; but later he rallied manfully to the cause of the defence of the Union, and his newspaper rang with impassioned appeals for the freedom of the slaves held in bondage in the South. He incessantly urged a more vigorous prosecution of the war, and called upon President Lincoln to take every possible measure for the emancipation of the Southern bondmen.