London — Pressures are piling up on Prime Minister Margaret Thatcher to call a general election in June and take advantage of the ruling Conservative Party's soaring popularity and the comparative disarray of its political opponents. According to one recent public opinion poll, the Tories are now 15 percentage points ahead of the Labour party, and Mrs. Thatcher's personal popularity is far greater than that of the Labour leader, Neil Kinnock. Just a week earlier, two other opinion polls showed the Tories ahead by 11 to 12 points.
More crucial for the party's planners, the government has begun to command support from more than 40 percent of the electorate. This is the magic figure that the pundits say Thatcher must maintain if she is to be certain of returning to power for a third term as prime minister.
Thatcher does not have to call a general election until June next year. But British premiers seldom let their governments run for a full five-year term. They like to unleash the electoral forces several months ahead of time and take advantage of surges of popularity. In Britain, general election campaigns are short, sharp affairs and seldom run longer than four weeks.
Until a week or two ago, many Tory insiders were predicting that Thatcher would go for an October general election. Now the same people are saying that there is such a tidal wave of support for the Tories that if the decision to call an election is delayed for too long, some unforeseen setback might intervene and destroy the present opportunity of victory.
In the view of many observers, the most authoritative opinion poll in the past few weeks was carried out by Gallup early in April. It showed the Tories with 40.5 percent, the Liberal-Social Democratic Party alliance 29 percent, and Labour 28 percent.
The poll sample showed only 14 percent believing Mr. Kinnock would make the ``best leader.'' Two-thirds of the sample said that Labour's program, which includes nuclear disarmament and opposes the Tory government's trade union reform laws, is ``too extreme.''
For the Labour Party, the latest poll results contain little good news. They suggest that Kinnock's determined attempts to launch Labour under a ``red rose'' emblem and with ``caring'' social policies has run out of steam.
Thatcher is understood to be determined to launch a new political program if and when she returns to power. She wants to carry on with tax reform (Chancellor Nigel Lawson's budget a month ago sliced 2 percent off the basic rate of income tax), push through education policy changes, and mount an assault on inner city decay.
But until she gets a renewed mandate from the electorate she is not in the best position to spearhead such a campaign.
Although the public opinion polls look good for Thatcher, they could just conceivably be hiding some nasty shocks for the Tories. Kinnock says he would never agree to working with the alliance parties, but it is possible that Labour and the alliance, by combining, could rob Thatcher of an absolute parliamentary majority.
In fact, the alliance, jointly led by David Owen and David Steel, constitutes a strategic threat to Thatcher's hopes of a third term as prime minister. And there may soon be a signal that will suggest the extent to which alliance support is building.
On May 7, there will be local elections in England and Wales. In such votes the alliance frequently does well. If they score well at the local level, this might create a groundswell for Mr. Steel and Dr. Owen that their political forces can take advantage of at a general election.
May 7 thus looks like a critical date in the Thatcher countdown to general election day. If the alliance chalks up a lot of support, the prime minister may decide that the risk of the alliance and Labour combining is too great. But if the alliance does only moderately well, and the Tories continue to hold up in the opinion polls, Thatcher would probably be safe to assume that a June victory is hers for the taking.