Britain's Social Democratic Party is off and running

Leaping into the political unknown in a balze of national debate, Britain's new Social Democratic Party faces an uphill task ahead. So far it is seen here as having had remarkable success in winning support from many voters upset with the pendulum swing in recent years between Labour and Conservative governments.

But now its problems really begin. Are there enough disaffected voters ready to stick with it until the next general election set for sometime in 1984?

Can the Social Democrats forge a working alliance with the Liberal Party for that general election? Can it set up effective grass roots constituency groups? Can it sharpen and define its political platform (pro-European Community, pro-NATO, pro-mixed economy) without alienating its following?

A central problem was forseen by Shirley Williams, one of the four Social Democratic leaders, in a recent interview with this correspondent. Asked if she felt confident, she relied" "No, not totally. The two big parties might move back toward the center and then they could squeeze us out; but we are going on. . . ."

Polls show a Social Democratic-Liberal alliance pulling in about 40 percent support. This is unprecedented for a new breakaway party. The Labour Party is badly split between the far left and left-wing forces. Prime Minister Margaret Thatcher's Conservative government is at a low point after two years in office, with taxes and unemployment rising and industry suffering.

The question is how long that situation will last. The Social Democrats say they have received about 30,000 messages of support so far. Examples read by this correspondent in Mrs. Wiliams's office:

A lancashire Labour Party town counselor: "Marxists have taken over whole [ Labour] parties in the Midlands and Yorkshire. . ." A young man from Kent: "The politicians are tearing this country apart. . ." A Staffordshire trade union shop steward: "The working man really wants a level-headed, well balanced center party. . . ." A Liverpool Liberal Party supporter: "I am increasingly disillusioned with my party."

Already both Labour and Conservatives are devising strategies to attack and denegrate the new group. This itself illustrates how far the Social Democrats have come in a few short months. The counterattack was well underway even as the new party launched itself March 26 in an early morning London press conference, attended by more than 500 journalists from around the world.

The orthodox Labour Party headed by Michael Foot attacked Social Democratic members for " an act of dishonor" -- staying inside Labour ranks for so long. Mr. Foot's own stature as party leader has been seriously weakened by the new party going its own way. Mrs. Williams, David Owen, Roy Jenkins, and William Rodgers all held senior office in the Labour party before leaving.

Mr. Foot called on the 13 member of Parliament in the new party to resign at once and stand again under their new colors. The 13 are not likely to do so.

another strategy shaping up: Mr. Foot could team up with Prime Minister Thatcher, who herself has described to Social Democrats as "slow-motion socialism."

Mr. Foot is already pressing Mrs. Thatcher to strengthen the Labour Party in the House of lords by creating a new group of Labour peers from the ranks of members of the House of Commons.

The move would force by-elections in the seats of the new peers (in the British system, members of the Commons are elected, but Lords are not).

If Mrs. Thatcher and Mr. Foot elevate Labour members from safe labour seats, the Social democrats would face a dilemma.

Mrs. Williams and Mr. Jenkins currently hold no Commons seat and they are anxious to get back into Parliament. Contesting new by-elections is one way to do that quickly.

But contesting safe Labour seats would also risk defeat. Failure to contest could lead to intense criticism. Either way, Social Democratic momentum would be set back.

The Social Democratic strategy is to choose by-elections where Mrs. Williams and Mr. Jenkins would have good chance.

Conservative strategy so far is to try to dismiss the new group as "yesterday's men," as party chairman Lord Thorneycroft puts it. Tories rub their hands at the strife on the left. But many Conservatives are also gravely concerned at the undoubted appeal the new party is having today on voters angry at Mrs. Thatcher's monetarist policies.