His priorities were "order, moderation, compromise, and party unity", which he tried to place ahead of his personal views on political issues.[53] As he would as president, Pierce valued Democratic Party unity highly, and saw the opposition to slavery as a threat to that.[54]
Democratic James K. Polk's dark horse victory in the 1844 presidential election was welcome news to Pierce, who had befriended the former Speaker of the House while both served in Congress. Pierce had campaigned heavily for Polk during the election, and in turn Polk appointed him as United States Attorney for New Hampshire.[55] Polk's most prominent cause was the annexation of Texas, an issue which caused a dramatic split between Pierce and his former ally Hale, now a U.S. Representative. Hale was so impassioned against adding a new slave state that he wrote a public letter to his constituents outlining his opposition to the measure.[56] Pierce responded by re-assembling the state Democratic convention to revoke Hale's nomination for another term in Congress.[57] The political firestorm led to Pierce severing ties with his longtime friend, and with his law partner Fowler, who was a Hale supporter.