Contenders for prime minister post court party with rising clout. POWER BROKER IN PAKISTAN

After years of resentment at being shut out of power, the Mohajirs of Pakistan are flexing their political muscle. The Mohajir National Movement (MQM) represents Muslim refugees who poured across the border from India 40 years ago. Launched just five years ago, the party placed third in the Nov. 16 national election.

As a result, it is a key power broker in the scramble underway for the prime minister's post. The MQM is being courted by top vote-getter Benazir Bhutto and second-place challenger Nawaz Sharif.

Ms. Bhutto, the opposition leader, won 92 seats in the national assembly elections against 54 for Mr. Sharif's pro-establishment coalition, the Islamic Democratic Alliance.

The MQM's 13 seats, coupled with the seven of fourth-place finisher Jamait-i-Ulema-Islam (JUI), a moderate Islamic party, could give Bhutto the edge in taking majority control of the national assembly. Pakistani President Ghulam Ishaq Khan has the power to appoint as the new prime minister whoever can command a parliamentary majority.

The MQM's meteoric rise culminates years of bitterness among the Mohajirs - the word means refugee in Urdu - and their descendants. The Indian Muslims fueled the movement to create a Muslim nation, Pakistan, separate from majority Hindi India, only to face widespread discrimination in jobs and schooling in their chosen country, Mohajir leaders say. In recent years the discontent spilled over into spiraling ethnic violence between the Mohajirs and nationalists in Sindh province, where most of the immigrants settled. MQM militants also played a leading role in clashes with Pashtuns, the people from northwestern Pakistan.

The MQM, which has wide support among poor unemployed youths in urban slums, began making political waves a year ago when it swept local elections in Sindh. Politics there traditionally have been dominated by large rural landlords. MQM's control of the two largest Sindhi cities, Karachi and Hyderabad, are a key bargaining tool in forming the national government.

``This election was a referendum in which the Mohajirs gave the MQM a mandate to take their problems to the national level,'' says Altaf Hussain, MQM's charismatic leader. ``The MQM is the only party that has broken out of political tradition and brought young people from lower classes into the political process.''

Mr. Hussain, a 36-year-old pharmacist, is one of a new breed of young Pakistani leaders emerging from the national elections. Many of the country's older politicians, including most of those associated with the late strongman Mohammed Zia ul-Haq, were eliminated in the balloting.

The chiefs of all four parties are under 40. In addition to Bhutto, Sharif, and Hussain, the group also includes Maulana Fazlur Rahman, whose religious JUI party is important for Bhutto in the volatile northwest frontier province.

Bhutto's coalition-building with the MQM could quiet the tensions in Sindh by giving the party national power. She could ease Mohajir alienation which has fueled communal tension, tearing the province and its main city of Karachi in recent years.

However, Bhutto likely faces days of uncertainty before she is allowed to take charge. She is locked in a constitutional dispute with the country's President, who refused her demand to allow her to form a government immediately. During the Zia years, the late dictator changed the Constitution to invest widespread powers in his office and thus secure his grip on power.

Bhutto claims the delay in naming her prime minister is intended to strengthen Sharif, a wealthy businessman with ties to the bureaucracy and military.

Bhutto charges that Sharif is luring smaller parties with government patronage and is intimidating independent representatives. She fears that her rival will increase his hold on the assembly in Punjab, Pakistan's most powerful province. That could make it more difficult for Bhutto, who lost three out of four provincial assembly elections, to govern.

``The delay in transferring power is giving rise to the suspicion that an effort is being made to subvert the political process,'' she said.