On 1 November 1990, Howe, by then the last remaining member of Thatcher's original 1979 cabinet, resigned from his position as Deputy Prime Minister, ostensibly over her open hostility to moves towards European Monetary Union.
On 14 November, Michael Heseltine mounted a challenge for the leadership of the Conservative Party. Opinion polls had indicated that he would give the Conservatives a national lead over Labour. Although Thatcher led on the first ballot with the votes of 204 Conservative MPs (54.8%) to 152 votes (40.9%) for Heseltine and 16 abstentions, she was four votes short of the required 15% majority. A second ballot was therefore necessary. Thatcher initially declared her intention to "fight on and fight to win" the second ballot, but consultation with her Cabinet persuaded her to withdraw. After holding an audience with the Queen, calling other world leaders, and making one final Commons speech, on 28 November she left Downing Street in tears. She reportedly regarded her ousting as a betrayal. Her resignation was a shock to many outside Britain, with such foreign observers as Henry Kissinger and Gorbachev expressing private consternation.