LONDON — IN a bid to restore the waning popularity of his Conservative Party and regain the initiative from the Labour Party opposition, Prime Minister John Major has sunk what his predecessor, Margaret Thatcher, only two years ago called "the flagship of my administration." The poll tax, a highly unpopular local government levy on all adults, is to be replaced by a tax geared to the value of individual properties.
The new measure, which members of the government see as representing a decisive break by Mr. Major with the Thatcher era, received a cordial welcome from Conservatives in the House of Commons on Tuesday, when it was unveiled by Michael Heseltine, the environment secretary.
Mr. Heseltine's role in devising and announcing details of the tax underlined the extent to which Mrs. Thatcher's influence over government policy has evaporated. Heseltine challenged her for the Conservative leadership last November and opened the contest that resulted in the choice of Major as prime minister.
One of Heseltine's main themes in his failed leadership bid was the error Thatcher had made in introducing a tax hated by Conservatives and Labour supporters alike.
Chris Patten, the Conservative Party chairman, greeted the announcement with the comment: "We now have the opportunity to go on the political attack, and we intend to seize it."
Recalling that the Labour opposition had persistently described the poll tax as a fox that they were delighted to shoot at, Mr. Patten added: "We have not only shot the fox - we have buried it six feet under."
Major's chief aim in getting rid of the poll tax was to put an end to the deep divisions within his party, created by a measure that in millions of cases greatly increased the amount adults had to pay for local government services.
Immediately after his election as party leader and prime minister, Major opened up a Conservative lead over Labour in the opinion polls. His popularity was buttressed also by his handling of Britain's part in the Gulf war.
But since Iraq's defeat, the spotlight has fallen on domestic political issues, and Major was accused by the government's opponents of a lack of firm leadership. He has not been helped by unemployment, which has risen above 2 million, and by an economic recession, which the leader of the Institute of Directors said Tuesday was the government's fault.
These factors sharply reduced the popularity of the prime minister and the government and raised Labour's hopes of winning the next general election, due to be held in mid-1992 at the latest.
Major, however, is able to point to a drop in inflation of nearly 3 percent since he became prime minister, and this week Norman Lamont, the chancellor of the Exchequer, forecast a recovery in economic output in the second half of this year.
Cecil Parkinson, a former Conservative Party chairman and leading Thatcherite, said he was "very happy" with the decision to replace the poll tax with a charge that would divide properties into seven "bands," according to their capital value. He said he accepted Heseltine's assurance that two out of three households would be better off.
The morning after Heseltine gave details of the new measure, the Conservatives, Labour, and the small Liberal Democrat Party held press conferences aimed at improving their chances of doing well in local government election to be held in England and Wales on May 2.
Neil Kinnock, the Labour leader, said the electorate would not be impressed by a measure that reflected the Conservatives' mood of panic and indecision.