ZULFIKAR Ali Bhutto said in Lahore that Punjab and Sind, the two provinces in the west wing which have given him maximum support, constitute what he calls "the bastion of power". And he repeated his assertion that power in the federal government must be "equally shared" by the two major parties representing the two wings. This immediately provoked the secretary general Taj Uddin Ahmed of the Awami League to declare just what the rank and file of the party wanted to hear: that with its east wing absolute majority in the national assembly, his party was "competent" to frame the constitution and later to form the government at the centre, "with or without co-operation from another party".

Few observers could regard these statements as policy declarations of likely allies whose co-operation is vital if Pakistan is to have a constitution within 120 days of the first session of the newly-elected national assembly.

Yet, despite statements which reflect a gradual hardening of attitudes in the two wings, the case for cooperation between the Awami League and the PPP (Pakistan People's Party) is far from shattered. In fact, as time goes on and the two parties prepare for the first session of the national assembly probably in the first week of February - the reasons for developing maximum possible understanding between the Awami League and the PPP are likely to get stronger. For Bhutto and Sheikh Mujibur Rahman there will be no other choice.

The need for this co-operation can best be assessed only in the context of President Yahya Khan's position vis-a-vis the constitution and in the overall perspective of political polarisation in the two wings of Pakistan.

Indeed, with its absolute majority in the national assembly, the Awami League is "competent" to obtain the simple majority vote for any kind of draft it places before the house. But it is powerless to persuade President Yahya Khan who, under his Legal Framework Order, retains the power of veto.

In fact, by now this must be quite clear to Sheikh Mujib that the president is hardly likely to accept a draft constitution not actively approved by both the Awami League and the PPP. It can be argued that the president can reject a draft constitution that has been approved by a simple majority in the national assembly - in other words, by supporters of the Awami LeagueÑ only at the risk of provoking another mass upsurge in East Pakistan which could even lead to the break-up of the country into two or more sovereign states.

However the moderate elements in the country now pleading for co-operation between Bhutto and Mujib point out such an upsurge may only suit the army which, now distinguished from the president, is yet to come to terms with the new realities in Pakistan's politics. The army might then take the first opportunity to impose its own rule - a militant dictatorship of conventional pattern over the whole country and govern East Pakistan in its own way as long as it can.

In stating their case for an alliance between Sheikh Mujib and Bhutto, the moderate elements in the two main parties have also warned against the danger of the army making an alliance with the "reactionary vested interests" in West Pakistan opposed to both the Awami League's six-point programme and the PPP's call for drastic socioeconomic reforms.

These warnings may not be totally premature. After all, all well-informed observers in Dacca know that emissaries from right wing politicians in West Pakistan, in their bid to drive a wedge between the League and the PPP, have already sought to establish their contacts with Sheikh Mujib, only to be cold-shouldered .

Another group, also representing big business and top industrialists in West Pakistan, has been trying to mobilise political forces against the concept of regional autonomy, in the hope that their campaign will eventually make co-operation between Bhutto and Mujib difficult, if not impossible.

Many observers may, therefore, assume that a series of somewhat negative reasons will provide the basis for this all-important co-operation between the Awami League and the PPP. But this is not entirely correct. Although these negative reasons -- especially the attempts by big business to thwart the constitutional process and the role of the army - are of immediate concern, there are several positive angles to this need for an alliance. Not only must a constitution be framed; the country must be given its first popular representative government. Although the two parties conducted their election campaigns on somewhat separate issues, they do complement each other in the overall political context. Bhutto's socialism and Sheikh Mujib's new social order can hardly come about without cooperation Whatever differences the two leaders have over Pakistan's relations with the outside world, especially with China, India and the United States, they may eventually prove to be more a disagreement on emphasis than on fundamental principle.

Some observers in Lahore feel a coalition between Bhutto and Mujib would be perfectly acceptable to the United States as well as to China, both of which, the observers believe, want to see a stable Pakistan. Almost certainly India takes the same view.