His legislative career, which stretched over several sessions, for he was thrice re-elected, in 1836, 1838, and 1840, was not remarkably brilliant. He did, indeed, not lack ambition. Together with his reputation and influence as a politician grew his law practice, especially after he had removed from New Salem to Springfield, and associated himself with a practitioner of good standing. He had now at last a fixed position in society. He became a successful lawyer, less, indeed, by his learning as a jurist than by his effectiveness as an advocate and by the striking uprightness of his character; and it may truly be said that his vivid sense of truth and justice had much to do with his effectiveness as an advocate.
His time had not yet come when, in 1846, he was elected to Congress. In a clever speech in the House of Representatives, he denounced President Polk for having unjustly forced war upon Mexico, and he amused the Committee of the Whole by a witty attack upon General Cass. More important was the expression he gave his anti-slavery impulses by offering a bill looking to the emancipation of the slaves in the District of Columbia, and by his repeated votes for the famous Wilmot Proviso, intended to exclude slavery from the Territories acquired from Mexico. But when, at the expiration of his term, in March, 1849, he left his seat, he gloomily despaired of ever seeing the day when the cause nearest to his heart would be rightly grasped by the people, and when he would be able to render any service to his country in solving the great problem. Nor had his career as a member of Congress in any sense been such as to gratify his ambition. Indeed, if he ever had any belief in a great destiny for himself, it must have been weak at that period; for he actually sought to obtain from the new Whig President, General Taylor, the place of Commissioner of the General Land Office, willing to bury himself in one of the administrative bureaus of the government. Fortunately for the country, he failed; and no less fortunately, when, later, the territorial governorship of Oregon was offered to him, Mrs. Lincoln’s protest induced him to decline it. Returning to Springfield, he gave himself with renewed zest to his law practice, acquiesced in the Compromise of 1850 with reluctance and a mental reservation, supported in the presidential campaign of 1852 the Whig candidate in some spiritless speeches, and took but a languid interest in the politics of the day. But just then his time was drawing near.