The 1968 presidential campaign of Richard Nixon, the 36th vice president of the United States, began when Nixon, the Republican nominee of 1960, formally announced his candidacy, following a year's preparation and five years' political reorganization after defeats in the 1960 presidential election and the 1962 California gubernatorial election. En route to the Republican Party's presidential nomination, Nixon faced challenges from Governor George Romney of Michigan, Governor Nelson Rockefeller of New York, Governor Ronald Reagan of California, and Senator Charles Percy of Illinois. Nixon won nine of the thirteen state primaries held that season, although due to the population of his state, Governor Reagan won the popular vote while carrying only California. These victories, along with pledged delegate support from states not holding primaries, secured Nixon the nomination on the first ballot of the Republican National Convention, where he named Governor Spiro Agnew of Maryland as his running mate. In the general election, Nixon emphasized "law and order", positioning himself as the champion of what he called the "silent majority". Running well ahead of his opponent, incumbent Vice President Hubert Humphrey, his support slipped in the polls following his refusal to partake in presidential debates, and following an announcement from President Lyndon B. Johnson that a halt in the bombing of Vietnam had been negotiated. Winning a close election on November 5, 1968, Nixon and Agnew were inaugurated as the 37th president of the United States and 39th vice president of the United States, respectively, on January 20, 1969. He was the first vice president since Martin Van Buren in 1836 to be elected president without first having succeeded to that office through the death of his predecessor, and the first non-incumbent vice president to be elected president. (en)