LONDON — Former Defense Secretary Michael Heseltine formally announced his candidacy Wednesday for the top post in Britain's Conservative Party.
The move confronts Prime Minister Margaret Thatcher with her most daunting political challenge yet. If Heseltine wins the balloting among Tory members of the House of Commons, he would replace Thatcher as prime minister, 11 years into her residency at 10 Downing St.
Heseltine, 57, said he had decided to try for the leadership because of Thatcher's lackluster support for Britain's role in the European Community.
Heseltine said his views are similar to those of Geoffrey Howe, who on Tuesday issued the most severe denunciation of the Thatcher government ever made by a former member of her Cabinet.
Heseltine's supporters believe that Thatcher has become a liability to the party, with her standings in the public opinion polls at a near-record low.
Thatcher has been running considerably behind Heseltine in national public opinion polls, but there has been no authoritative assessment of her strength among Conservative members of Parliament.