The presidency of Ronald Reagan began at noon EST on January 20, 1981, when Ronald Reagan was inaugurated as the 40th President of the United States, and ended on January 20, 1989. Reagan, a Republican from California, took office following a landslide victory over Democratic incumbent President Jimmy Carter in the 1980 presidential election. Haig left the cabinet in 1982 after clashing with other members of the Reagan administration, and was replaced by another former Nixon administration official, George P. Shultz. By 1982, National Security Advisor William P. Clark Jr., Ambassador to the United Nations Jeane Kirkpatrick, and CIA Director Casey had established themselves as the major figures in the formulation of the administration's foreign policy. Shultz eventually emerged as the administration's most influential foreign policy figure, moving the administration towards a less confrontational policy with the Soviet Union. Regan frequently clashed with First Lady Nancy Reagan, and he left the administration in the wake of the Iran–Contra affair and Republican losses in the 1986 mid-term elections. Regan was replaced by former Senate Majority Leader Howard Baker.