The declaration of war against Mexico brought forth an outpouring of patriotic and martial enthusiasm in the United States, both in the nation's capital and across the country. The war bill passed handily in the House of Representatives by a vote of 174 to 14, while in the Senate the vote was even more lopsided--40 to 2. When the War Department asked the states to raise 50,000 volunteers, the response was overwhelming and immediate. The quotas of some states were filled so quickly that young men moved to neighboring states to enlist. By some estimates more than 200,000 American men answered the call for volunteers.
Yet the war effort would also serve as a lightning rod for the bitter partisan rivalry between Democrats and Whigs. The party of Jackson had often criticized the nation's military academy at West Point as an elitist, government-funded institution for the sons of well-connected and well-to-do families, a reputation that was not entirely undeserved. Resentful of the criticism, the army's high command tended to favor the Whig Party. Winfield Scott, the nation's highest ranking general, had already been touted as a potential Whig presidential candidate even before the war began. Democrats quickly sought to neutralize the Whigs' influence over the army's top brass by authoring emergency legislation to expand the high command, a blatantly partisan attempt to supersede long-serving Whig generals like Scott with party loyalists. The bill allowed Congress to create two additional major generals and four brigadier generals in the regular army. Although the Whigs in Congress did manage to reduce the number of new positions to one major general and two brigadiers, the move seemed to confirm their suspicions of Democratic partisanship.
Unwilling to allow the ambitious Scott the opportunity to become a national hero and thereby ensure his nomination as the Whig presidential candidate in 1848, the administration gave the highly coveted task of leading the invasion of Mexico to Zachary Taylor, whose political views were unknown. The plan backfired, however, when Taylor, after a series of successes in northern Mexico, began to entertain political ambitions of his own. Friction between Taylor and the administration flared into outright hostility amid reports that the general was considering a presidential bid. When the administration decided to open a southern campaign as the year 1846 drew to a close, Polk refused to consider Taylor. With no other option available to him, he turned, reluctantly, to General Scott to lead the invasion of Veracruz.
Partisan tensions were also heightened by the scramble for patronage, or what had come to be known as "the spoils system." Both parties used patronage as a means to reward supporters and build strong political organizations, a practice that had become widespread by the 1840s. From the outset of Polk's presidency, hordes of office-seekers encamped daily at the White House, all bearing letters of introduction from Democratic leaders in their home states, asking the president to appoint them to federal positions. With the declaration of war, the demand for patronage increased with the size of the army. The creation of a new volunteer army required Polk to appoint dozens of brigade and division commanders, posts that were eagerly sought by Democratic political leaders. Sensitive to Whig allegations that he was putting the interests of his party first, the president made a point of reserving some lower grade commands for members of the opposition, although such modest efforts did little to stem the criticism. In addition, Congress more than doubled the size of the regular army (from 8,000 to roughly 20,000), creating a new command structure with hundreds of new officers' commissions, as well as a greatly expanded War Department staff for logistical and support roles. Within days after the declaration of war, Polk was inundated with requests from congressmen seeking commissions for themselves, as well as for influential party leaders in their districts. "The pressure for appointments," Polk noted in his diary, "is beyond anything I have witnessed since I have been President."
The bickering over military appointments was no less acrimonious at the state level. Since the war bill passed by Congress left the task of organizing volunteer regiments to the individual states, governors enjoyed considerable latitude to appoint party loyalists to positions of command. In one particularly notorious case, partisan rivalries played a direct role in fomenting a mutiny. Whig governor William A. Graham of North Carolina tapped two prominent members of his party to serve as field commanders of the North Carolina First Infantry. The enlisted men, most of whom were Democrats, insisted on the right to appoint their own regimental officers. The appointments caused so much ill will that the troops under the command of Colonel Robert T. Paine rioted, attacking his tent. Paine responded by firing his pistols into the crowd, killing one volunteer and wounding another. An inquiry into the affair led to the dismissal of two Democratic officers. North Carolina Democrats took their case to the White House, prompting President Polk to intervene, ordering the two ringleaders reinstated.
Though Polk professed to loathe the spoils system, this did not prevent him from using it to his advantage. Suspicious of his top generals in Mexico, the president received regular reports from high-ranking officers in the volunteer army, all loyal Democrats, to keep him apprised of developments in the field. Invariably, this network of informants portrayed Scott and Taylor in an unfavorable light, leaving the president to conclude that both men were working to undermine the administration's war aims. The intense partisanship within the high command finally came to a head after the fall of Mexico City in September 1847. Democratic members of Scott's staff, including General Gideon Pillow, a close friend of the president, claimed credit for the victory. Furious, Scott ordered the arrest of Pillow and two other Democrats. Once again the president intervened, recalling Scott to Washington. In the final months of the occupation of the Mexican capital, U.S. troops would be led by William O. Butler, a former Democratic congressman from Kentucky.