As president, Pierce simultaneously attempted to enforce neutral standards for civil service while also satisfying the diverse elements of the Democratic Party with patronage, an effort which largely failed and turned many in his party against him. He was a Young America expansionist who signed the Gadsden Purchase of land from Mexico and led a failed attempt to acquire Cuba from Spain. He signed trade treaties with Britain and Japan, while his Cabinet reformed their departments and improved accountability, but these successes were overshadowed by political strife during his presidency. His popularity declined sharply in the Northern states after he supported the Kansas–Nebraska Act, which nullified the Missouri Compromise, while many whites in the South continued to support him. Passage of the act led to violent conflict over the expansion of slavery in the American West. Pierce's administration was further damaged when several of his diplomats issued the Ostend Manifesto calling for the annexation of Cuba, a document which was roundly criticized. He fully expected to be renominated by the Democrats in the 1856 presidential election, but was abandoned by his party and his bid failed. His reputation in the North suffered further during the American Civil War as he became a vocal critic of President Abraham Lincoln.