Note: The map is not fully accurate to the actuals borders of this alt-USA. The exclusion of Washington is meant to roughly approximate the borders of this TL, which follows the Columbia River, which unfortunately I could not superimpose on the map.
The
1848 United States presidential election was held on November 7, 1848, the first US presidential election to take place on the same day in all states. Vice-President Willie Mangum of North Carolina, running for the incumbent Whig Party, defeated William R. King of Alabama, the Democratic candidate.
Incumbent President William Henry Harrison had overseen a term that was considered fairly successful; as the first Whig president, he had enacted the platform of his party to great success, spending much of 1845 allocating funds for internal improvements, raising tariffs, and chartering the Third Bank of the United States. The depression that had followed the Panic of 1837 was fully a thing of the past, which enhanced Harrison's popularity. However, the looming issue of Texas became a growing problem. While during Van Buren's second term the issue had largely been fought on the Senate floor by Vice-President Tyler and John C. Calhoun, the campaign of 1844 had brought the issue to the fore; in particular, Harrison's victory had rested on the backs of considerable southern support, which left many Whigs feeling indebted to the region. Henry Clay, the foremost legislator among the Whigs, had some personal antipathy around the issue because mostly due to Tyler's constant forcing of the issue during his term severely annoying him, but lacked any ideological opposition to it; ultimately, Clay, along with the rest of the Whigs and the Democratic leadership, concluded that a treaty of annexation needed to be drawn up, and despite Van Buren's considerable lobbying against it, the Texas annexation treaty was able to muster two-thirds of the Senate to pass, overcoming northeastern opposition by attracting northwestern support by promising them a resolution to the shared Anglo-American occupation of Oregon. They also threaded the needle of Senate balance by admitting Texas and Florida, both slave states, alongside the new free states of Wisconsin and Iowa.
The problem, ultimately, was that Harrison, a former military man, worked faster than Clay or his Secretary of State, Daniel Webster. Clay and Webster, for all their differences, wanted to negotiate peaceful resolutions with Mexico and the United Kingdom to establish the borders with them; Harrison, however, quickly moved to occupy and annex Texas. In the confusion, a diplomatic incident occurred when some Texans and Mexicans both tried to occupy disputed land and a scuffle in which the Mexicans were killed broke out. Mexico demanded reparations for the incident; Harrison refused. Ultimately, this ended in the breakout of the Mexican-American War, which the US handily won. Harrison negotiated a huge concession of land from Mexico, which made him very popular. However, he had not yet negotiated the settlement of the Oregon issue when the war broke out. During the war, Britain had demanded the border follow the Columbia River; Webster had tried to negotiate them back to the 40th parallel but failed, and with the small US army embroiled in Mexico, they were forced to accept a border that followed the 40th parallel to the Columbia River before following in to the Pacific Ocean. In any case, Harrison did succeed in gaining a Pacific coast for the US, though some northwesterners did feel betrayed by the deal with the British.
Overall, the Whig position for 1848 was considered strong. President Harrison had pledged in his inauguration speech to serve only a single term, and so their nomination was wide open. As their convention gathered at Philadelphia, most considered Henry Clay, the eldest statesman of the party, the likely nominee. Clay indeed led on the first ballot, but was short of majority, to his own surprise; as it turned, a large number of southern delegates he had been counting on had instead chosen to back Zachary Taylor, an apolitical general of the Mexican-American War who had little interest in the Whig nomination. He also lost support to Winfield Scott, another Mexican-American War general who was a more doctrinaire Whig than Taylor, and to Webster, who commanded most northeastern delegates. As the ballots went on, Clay failed to make gains but instead lost support; southerners considered him to have been insufficiently supportive of Texas annexation, while northern delegates were more receptive to him but, after a number of health scares during Harrison's tenure, were put off by Clay's age. Clay, acutely aware this might be his last chance at the presidency, stubbornly persisted; meanwhile, none of the other candidates were able to take advantage of Clay's weakness, as Scott and Taylor were both too disinterested in the nomination to seriously pursue it and the former too closely associated with free-soil Whigs like William Seward for southerners. Webster, meanwhile, had no appeal outside the northeast. The deadlock persisted until the fifteenth ballot, when the North Carolina delegation switched its votes to Vice-President Willie Mangum; many southern Taylor delegates moved to him on the sixteenth ballot. His agents consolidated the support of northwestern and southern delegations as he decided whether or not he wanted the nomination, as he was reluctant to betray his friend Clay. Ultimately, the Senator from Kentucky accepted he could not gain the nomination and endorsed Mangum once he had secured the promise of a Cabinet spot; the vice-presidential nomination was given to Millard Fillmore, a moderate Whig from New York.
The Democratic convention, in comparison, was chaos. The party was increasingly divided by the severe disagreements between the northern Van Buren-dominated wing and its planter-dominated southern wing. The proposal of popular sovereignty regarding slavery in the Mexican cession was the compromise that both sides hated; Van Buren, for the rest of his life, would at least be satisfied he managed to sideline champions of that policy, like Lewis Cass, at the 1848 convention. Nonetheless, Van Buren was not in a strong position for the convention; many believed the south had to be given an olive branch. Van Buren further hurt himself by exploring the possibility of nominating him for a third term, which did not go over well on the convention floor. Ultimately, it had little effect beyond hurting the campaign of Levi Woodbury, the primary Van Burenite candidate. As the convention continued, it became clear that, with the compromise of popular sovereignty unable to gain a majority, the Van Burenites and the slavers would have to slug it out. However, the process of finding a candidate was less simple than it should've been. Van Buren's trial lead balloons over his potential third term wasted time that could have helped Woodbury, while the southerners struggled to find one acceptable to the whole country; dark horse James K. Polk was facing a bout of ill health (but ultimately lived until 1870), while John Tyler and Richard M. Johnson were unable to attract support. Ultimately, around the fiftieth ballot, William R. King of Alabama, a moderate southerner who had entered the convention hoping for the vice-presidential nomination, gained steam as a presidential candidate; while he was circumspect about the prospect of running, once the nomination had been secured for him on the fifty-fourth ballot, King elected to accept it, with Woodbury being given the vice-presidential nomination as a sop to Van Buren. The ex-president, for his part, was furious with the result of the convention and considered organizing a third party run, but instead elected to remain outside of the contest, pointedly refusing to endorse King.
In the end, the Democrats fell completely flat on their faces. Harrison was a successful and popular president, which aided his party; and the gamble of gaining southern support failed, as gaining Mississippi and Alabama was more than made up for by the loss of New York and Pennsylvania, even when accounting for gains in Texas, Wisconsin, Iowa, and Indiana. Moreover, Mangum held closely contested southern states like Georgia and Virginia and gained the new state of Florida, so King failed to deliver much in his home region. Ultimately, the party was too divided and the Harrison too popular, and so it is little surprise that they lost the 1848 election.