The right-wing clerical Islamic Republican Party tonight clung to its lead but remained a handful of seats short of outright control of the new 270-seat parliament that Ayatollah Ruhollah Khomeini has said will resolve the hostage crisis with the United States.

With about two-thirds of the voting districts in yesterday's long delayed runoff election declared, the Islamic Republican Party and its "grand coaltion" allies won 59 seats to 62 divided among an array of factions dominated by President Abol Hassan Bani-Sadr's followers and independents.

The runoff results so far were less favorable for the Islamic Republican Party than those of the March 14 first round.

Then, the clerical party captured two-thirds of the approximately 100 seats decided by the absolute majority required for outright election.

Accurate calculation were hampered by the postponement of voting in 22 districts either disrupted by fighting in the western province of Kurdistan or still under investigation because of first-round charges of vote rigging. Final results of the second round were promised for next Wednesday, but Iranian election results have been delayed in the past.

Various politicians have mentioned dates ranging from May 26 to June 5 for the convening of the parliament. If, as some insiders have suggested, the hostage question is the first substantive order of business, observers doubted meaningful debate would start before mid-June since the legislators must first organize.

Public attention, meanwhile, has shifted to Bani-Sadr's success in enlisting Khomeini's crucial backing for a provisional government expected to be named in the next few days.

Even major Islamic Republican Party leaders have fallen into line despite their obvious distaste for a solution that strengthens their main rival and deprives them of the privilege of naming the prime minister they feel is their constitutional right as the biggest parlimentary group.

In a newspaper interview today, BaniSadr insisted that the new provisional government "must have the public's confirmation" rather than parliament's. Left unsaid was his calculation that any such government backed by Khomeini could not be opposed by the clerical party in parliament and thus would have an open-ended duration.

Islamic Republican Party leaders appear determined to limit the life of a provisional government to two months in hopes of then, being able to name their own Cabinet.

Insiders reported that some leading candidates for the prime minister's job are insisting that they will not take the post on a two-month basis.

Meanwhile, the Swiss Embassy, which represents American interests here, was reported to have made a fresh attempt to established the whereabouts of freelance journalist Cynthia B. Dwyer, of Buffalo, N.Y.

She has been held incommunicado since Monday night. At the time of her arrest at the Hilton Hotel, the Pars news agency quoted Revolutionary Guards as saying the woman, 49, had admitted to spying for the Central Intelligence Agency.

The new approach was made through Bani-Sadr's office after an earlier effort to elicit information from the Foreign Ministry failed to produce any results other than confirmation of her detention.