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 to his antislavery 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.
The peace promised, and apparently inaugurated, by the Compromise of 1850 was rudely broken by the introduction of the Kansas- Nebraska Bill in 1854. The repeal of the Missouri Compromise, opening the Territories of the United States, the heritage of coming generations, to the invasion of slavery, suddenly revealed the whole significance of the slavery question to the people of the free States, and thrust itself into the politics of the country as the paramount issue. Something like an electric shock flashed through the North. Men who but a short time before had been absorbed by their business pursuits, and deprecated all political agitation, were startled out of their security by a sudden alarm, and excitedly took sides. That restless trouble of conscience about slavery, which even in times of apparent repose had secretly disturbed the souls of Northern people, broke forth in an utterance louder than ever. The bonds of accustomed party allegiance gave way. Antislavery Democrats and antislavery Whigs felt themselves drawn together by a common overpowering sentiment, and soon they began to rally in a new organization. The Republican party sprang into being to meet the overruling call of the hour. Then Abraham Lincoln's time was come. He rapidly advanced to a position of conspicuous championship in the struggle. This, however, was not owing to his virtues and abilities alone. Indeed, the slavery question stirred his soul in its profoundest depths; it was, as one of his intimate friends said, "the only one on which he would become excited"; it called forth all his faculties and energies. Yet there were many others who, having long and arduously fought the antislavery battle in the popular assembly, or in the press, or in the halls of Congress, far surpassed him in prestige, and compared with whom he was still an obscure and untried man. His reputation, although highly honorable and well earned, had so far been essentially local. As a stump-speaker in Whig canvasses outside of his State he had attracted comparatively little attention; but in Illinois he had been recognized as one of the foremost men of the Whig party. Among the opponents of the Nebraska Bill he occupied in his State so important a position, that in 1856 he was the choice of a large majority of the "Anti-Nebraska men" in the Legislature for a seat in the Senate of the United States which then became vacant; and when he, an old Whig, could not obtain the votes of the Anti-Nebraska Democrats necessary to make a majority, he generously urged his friends to transfer their votes to Lyman Trumbull, who was then elected.