Margaret Thatcher tendency to override collegiate opinion, contributed to discontent within her party. Thatcher removed Geoffrey Howe as Foreign Secretary in July 1989 after he and Lawson had forced her to agree to a plan for Britain to join the European Exchange Rate Mechanism (ERM). Britain joined the ERM in October 1990. 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. In his resignation speech on 13 November, Howe commented on Thatcher's openly dismissive attitude to
Third Thatcher ministry European Community. On 14 November, former cabinet minister Michael Heseltine challenged Thatcher's leadership. Thatcher polled higher than him in the first round of the leadership contest, but failed to gain an outright victory in the first round of voting. Within minutes of the result being announced, Thatcher informed reporters that she intended to let her name go forward for the second ballot. However, on 22 November, before a second round of the contest could take place, Margaret Thatcher announced her resignation as Prime Minister and Leader of the Conservative Party after more than 11 years, explaining that she was resigning