When Secretary of State Cyrus Vance met with Israel Foreign Minister Yidgal Allen in London the other day, Vance asked with an eye to resuming Middle East peace talks, how long it would take lagel to form a nw government following Tuesday's elections.

He was reportedly appalled to hear that the shortest time Israel had over taken to form a coalition government after an election was six weks, and the longest was four months.

With public opinion pools predicting the closest race in Israeli history, there is apprehension that it will again be extremely difficult for the winner to put together a strong, durable government. Some observers even see the possibility of a deadlock forcing new elections.

Shimon Peres and the Labor alignment, which has ruled Israel since its [WORD ILLEGIBLE] are expected to squeak through with the lowest plurality in its history. Even if the main opposition party, Likud, wins, however, the balance of power is likely to go to minor parties, the most important of which is the new, upstart reform party of Yigatel Yadin, the Democratic Movement for change.

Yadlin's party is not likely to win more than 15 to 18 seats in the 120 seat Parliament, according to recent polls, but with Labor and Likud likely to take anywhere from 30 to 44 seat apiece the difference between the leaders will be so slim that, as one Movement candidate put it, "The shape of Israel's new government could well depend on the pivotal balance of our hagging power."

No new party in Israel's history has gained so much support so fast, and the Movement, which now has 35,000 members, bases its appeal on a growing disillusionment with the old politics.

A noted archaeologist and former soldier, Yadin entered politics a year ago and formed his new party only in November. From the beginning, Yadin realized that his best chance of bringing about the reforms he advocates was to become the indispensable coalition partner to anyone trying to form a government. "Using the system to change it" is the way Yadin puts it, and his party intends to drive a very hard bargain indeed as the price for its cooperation.

The movement has published a list of seven demands it will impose on any coalition it is asked to join. This most controversials is the demand that the entire election system be reorganized and that elections be held under the new system within five years.

Perus had explained that it might be better to make a deal with Likud, which would give him at least four years before he would have to run again. But the different between the right-of-center-Likud and the Labor alignment are the great that such a merger would in the opinion of many observers, be [WORD ILLEGIBLE]

Rather than the [WORD ILLEGIBLE] system, in which voters face [WORD ILLEGIBLE] taken by the parties, Yadin's party wants a mixture of the present system and a regional and porportional representation as in England. Yadin says that if there were identifiable constituencies, politicians would be more responsive to the needs of the people.

He is also insisting on reduction of the present number of ministries and departments.

The movement will also insist on a plan to reduce inflation from its current rate of nearly 40 per cent to 15 per cent, on stricter labor legislation to curb wildcat strikes, on giving a high priority to closing the gap between rich and poor and on legislation to make the political parties themselves more [WORD ILLEGIBLE] in their selection of candidates.

The last of Yadin's demands is for an acceptance foreign and defense policy.

The movement's foreign and defense policy is [WORD ILLEGIBLE] between the platforms of Likud and Labor. Likud opposes any territorial concessions on the occupied West Bank, while Labor is on record as fevering at least some territorial concessions in exchange for peace in all the occupied territories.

Yadin's party proposes that the Jordan River be Israel's defense line in the east but opposes annexation of territory. It differs from Labor in that it would return territory on the West Bank only for a true peace and would opposed any interim agreements.

Movement candidate Eli Eyal, one of Yadin's close advisers, says that these are only minimum demands, adding: "If we get 20 seats I think we could ask that Yadin be prime minister."

There can be little doubt that this would prove unacceptable to Shimon Preres and the Labor Party, and it is unlikely that the movement will get as many as 20 seats. Nonetheless, labor is running scared and has been attacking the movement hard, warning that a vote for it could let Likud in the back door.

Yadin himself has captured something of a Wisconian image - perhaps a little naive politically but an idealist and a reformer who stands above the [WORD ILLEGIBLE] and corruption of traditional party politics. Compared to Likud and Labor, his campaign has been relatively clean.

Yadin's party has had little success in attracting the poor, the ill-educated and the disaffected. Voter profiles taken by the Smith Research Center show that the typical movement supporter is overwhelmingly young, Israel-born, well-educated, white-collar and of European origin rather than from the Jewish communities of the Middle East and North Africa.

For example, polls estimate that Movement is likely to capture 11 per cent of the total vote next Tuesday. By occupational breakdown, however 22 per cent of all white-collar workers intend to vote for the Movement while only 6 per cent of blue-collar workers intend to do so.

This is ironic because Yadin has constantly [WORD ILLEGIBLE] the disparity between rich and poor in his campaign, to the distress of his advisers who have seen that worker unrest, inflation and corruption in high places are more potent issues.

Yet Yadin's Movement has succeeded beyond most expectations and, whatsoever the outcome Tuesday, it may well be the Movement's "haggling power" that will decisive.