The new circumstance that intervened was the annexation of Texas. Texas was a vast territory, undefined as to its limits at that time, but covering an area eight or ten times greater than that of the largest state then in the Union. It included the present state of Texas, New Mexico, and a large area besides. It had been a part of Mexico, peopled chiefly by emigrants from the United States under whose inspiration it had revolted and achieved its independence as a republic. Its desire for annexation to the Union was quite natural and inevitable and but for slavery that desire would have been reciprocated throughout the United States. It was easily foreseen, however, that the annexation of this vast territory, lying as it did south of the line that set the limit to slavery, would open to that institution an opportunity of expansion scarcely less than that opened to free labor by the Missouri Compromise. The policy of annexation was bitterly opposed on this ground and additionally because of the practical certainty that annexation would involve a war with Mexico. Years before that time, Henry Clay had severely criticized the administration for having failed to insist upon our right to Texas as a part of the Louisiana Purchase, but now, in his anxiety to keep the slavery question out of politics because of the danger it involved to the Union, he was strongly opposed to the annexation policy. When, in 1844, it was deemed certain that Clay and Van Buren would be the rival candidates for president, those statesmen, being personal friends, met at Clay's residence at Ashland, and together planned to keep the Texan question out of the coming campaign. Their agreement was that each should publish a letter--at about the same time--opposing the annexation of Texas and the ratification of the treaty, which was then pending, to accomplish that purpose. The letters were published, but their effect was precisely the reverse of that which was intended. The Whigs nominated Clay by acclamation, but the Democrats of the South took offense at Van Buren's letter and nominated in his stead James K. Polk, an uncompromising advocate of annexation. Thus the painstaking effort that had been made by Clay and Van Buren to eliminate this annexation question from the presidential campaign had for its actual effect the making of that question the paramount issue of the contest. Thus the slavery question became again dominant in national politics with a greater disturbing force than ever. For the agitation in politics of a question concerning which men's consciences or self-interests are strongly enlisted--and this question involved both--must always and everywhere intensify feeling, arouse passion and consolidate partisan activity.