LONDON -- Facing an erosion of support for her continued leadership, Prime Minister Margaret Thatcher stunned Britain yesterday by suddenly resigning.
It was an abrupt and inglorious end to 11 1/2 years in power for the longest-serving British prime minister in this century.
Her decision opened the way for her Cabinet colleagues Foreign Secretary Douglas Hurd and Chancellor John Major to enter the second round of the battle for the leadership of the Conservative Party against Michael Heseltine, whose challenge triggered the prime minister's downfall.
The Conservatives will vote Tuesday. If none of the three candidates gets a simply majority of 187 votes, a runoff vote will be held Thursday
In a statement issued from Downing Street, Mrs. Thatcher said: "Having widely consulted among colleagues, I have concluded that the unity of the party and the prospects of victory in a general election would be better served if I stood down to enable Cabinet colleagues to enter the ballot for the leadership."
During the Cabinet meeting at which she announced her decision at 9 a.m., she gave a more personal reflection to her sudden turn of fortune. "It's a funny old world," she said. "I have won three elections and still believe I retain the overwhelming support of the party in the country."
On hearing the news, Mr. Heseltine, a former minister of defense who has campaigned behind the scenes to succeed her since he stormed out of the Cabinet in 1986, said: "This brings to an end a quite remarkable premiership. She has made a remarkable contribution to Britain's history and has led this country with distinction in the 1980s."
Opposition Labor leader Neil Kinnock said the news was "very good indeed" and called for an immediate general election.
Pressure on Mrs. Thatcher had mounted since Tuesday, when she failed by only four votes to defeat outright Mr. Heseltine's challenge to her leadership. In Paris with other leaders for the meeting on European security, the prime minister immediately put her name forward for the second round.
On Wednesday, she was still declaring: "I fight on. I fight to win."
But as the day wore on, it became clear that she was rapidly losing the support of Conservative members of Parliament. Many had voted for her out of loyalty in the first round. Now they felt free to look around. Many were tired of the prime minister's domineering style, her strident anti-European stance and her refusal to amend the bitterly unpopular poll tax, widely seen as an election loser.
Opinion polls consistently showed that Conservative chances of winning the next election would improve with Mr. Heseltine as leader.
Throughout Wednesday afternoon and evening, Cabinet ministers and parliamentary colleagues met with Mrs. Thatcher, some pressing her to continue the fight, others -- dubbed the "men in gray suits" -- urging her to resign. She faced, they said, a humiliating defeat, and unless she resigned, she blocked the field for other compromise candidates.
Neither Mr. Hurd nor Mr. Major, both popular with the party, felt able, out of loyalty, to enter against her.
At first she was defiant. As the Times editorial put it: "In went the gray suits. They laid the pistol on the table, tiptoed out . . . and heard a fusillade of shots aimed at their departing backs."
But early yesterday morning, she decided to resign.
It was perhaps the most difficult decision of her life, going against all her famed instincts to fight to the bitter end. Officially, she will remain as prime minister until a new leader of the Conservative Party is elected.
As the momentous news spread, crowds gathered outside Downing Street under chilly November skies.
Just after 12:30 p.m., Mrs. Thatcher was driven from her official residence, No. 10 Downing St., to Buckingham Palace to inform Queen Elizabeth II of her intention to resign.
Public reaction was mixed.
As her black Jaguar turned down Whitehall, some people booed. "She's out -- wonderful!" shouted a young woman.
"She's resigned -- good job and all," said another. "Everybody has their time. Her time had run out."
Others were saddened. "Tragedy, bloody tragedy," said a middle-aged man.
Another summed up that tragedy: "Mrs. Thatcher changed the country, but Mrs. Thatcher hasn't changed. The country has passed her by."
Yesterday afternoon, Mrs. Thatcher gave what will probably be her last major speech as prime minister to the House of Commons, defending her government in a "no confidence" debate sought by the Labor Party.
With no hint of nerves, she vigorously defended her record.
[The Conservatives defeated the no-confidence motion, 367-247, Reuters reported.]
As one backbencher put it, she went down "fighting like a lioness to the end."
[Also Thursday, the Associated Press reported, Mrs. Thatcher said that an additional 14,000 British troops would be sent to the Persian Gulf, bringing the total number of British soldiers in the region to more than 30,000.]
Now she must plan her life in the "post-Thatcher" era. She and her husband, Denis, own a house in Dulwich, a wealthy suburb of London. She will continue to be member of Parliament and so will appear in Parliament, almost unimaginably, as a backbencher.
In Britain, in the last few years, schoolchildren have taken to asking: "Can a man be prime minister?"
Next week, when Conservative members of Parliament vote for her replacement -- Mr. Heseltine, Mr. Hurd or Mr. Major -- they will get their answer.