Baker, James (Addison), III 1930- . US Republican politician. Under President Reagan, he was White House Chief of Staff 1981-85 and Treasury secretary 1985-88. After managing Bush's successful presidential campaign 1988, Baker was appointed secretary of state 1989. Baker, a lawyer from Houston, Texas, entered politics 1970 as one of the managers of his friend George Bush's unsuccessful campaign for the Senate. He served as undersecretary of commerce 1975-76 in the Ford administration and was deputy manager of the 1976 and 1980 Ford and Bush presidential campaigns. Baker joined the Reagan administration 1981. He has been criticized for the unscrupulousness of the 1988 Bush campaign. The most respected member of the Bush team, he has been described as an effective `prime minister'.