If Iran's latest offensive against Iraq in the Gulf war is crowned with success, the two principal beneficiaries -- in terms of internal domestic politics -- are likely to be:
* The Maktabi group of clerics, now in the ascendant, who favor exporting revolutionary Shia Islam and have the not-always-welcome support of the country's pro-Moscow communists in the Tudeh Party.
* Col. Ali-Sayyad Shirazi, the relatively youthful Army commander, who gets much of the credit for the success of Iran's March offensive in the war and could become a potential Iranian Cromwell or Bonaparte in the event of further sweeping victories over Iraq.
It is renewed proof of the resilience and durability of centuries-old Persian society. Iran has withstood without collapse three years of revolutionary upheaval and is now in the throes of an interclerical power-struggle at home and a war against Iraq, which it appears to be winning.
As anthropologist Michael Fischer of Rice University -- a specialist in Persian Shia Muslim social and political history -- warns, statements by outsiders on exactly what is going on behind the scenes in Iran are bound to be in some measure speculative. This is because of the Persians' addiction to secrecy and dissimulation. Another obstacle to getting at the facts is Iran's barring of resident Western correspondents and fairly strict control over those allowed in for short visits.
But there is evidence that internal politics are being dominated by a fierce struggle within the all-important Islamic Republican Party (IRP). The conflict is between two groups of mullahs or clerics: the Maktabi and the Hodjatieh.
(All clerics would call themselves ''Maktabi'' or ''properly schooled.'' But in the current power struggle, ''Maktabi'' is acquiring a particular connotation. ''Hodjatieh'' denotes loyalty to the Twelfth Imam of Shia Islam expected eventually to return to earth.)
The long-term issue in this power struggle is control of Iran once the octogenarian Ayatollah Khomeini is no longer on the scene.
The Maktabi group favors the eventual choice of a single man to succeed Ayatollah Khomeini in the role of Vilayat-e Faqih, or religious guardian. They believe that there is no room for separation between politics and religion, and that the Faqih should be as much a political as a religious supremo.
One of the most important members of the Maktabi is the deputy speaker of the Majlis (parliament) and chairman of its Foreign Affairs Committee, Hojatolislam Muhammad Musavi Khoeyni. He was a prime mover behind those who seized the hostages in the US Embassy in 1979.
The Hodjatieh clerics, on the other hand, want a collegiate group -- not just one man -- to exercise religious guardianship when Ayatollah Khomeini is no longer at the helm. They argue for a polity shaped by Shia Islam but would leave room for the government to be in secular, not exclusively religious hands. And they do not have as a prime aim the export of revolutionary Shia Islam.
The current President of the Islamic Republic, Sayed Ali Khamenei, and the current foreign minister, Ali Akbar Vellayati are linked with the Hodjatieh.
The Hodjatieh originally were identified with that element of the clergy most active in repression of members of the Bahai faith in Iran. At the same time, they are more resolutely anticommunist than the Maktabi.
On both sides, in these two groups, allowance must be made for apparently ideological stands being in fact tactical. The real struggle, as so often in Iran, is likely to be personal rather than ideological.
There is a third or swing group involved in the power struggle between the Maktabi and Hodjatieh groups. It is smaller than either but is led by an influential ''survivor'' in all the upheaval of the past three years, Hojatolislam Hashemi Rafsanjani, speaker of the Majlis.
Hojatolislam Rafsanjani appears to have money and patronage at his disposal, and his brother controls Iranian radio and television. All this, combined with his own official position, gives him leverage. His critics see him as an opportunist.
As many as eight of the 12 members of the IRP's political committee are thought to be Maktabi members. And the Maktabi reportedly have at least half of the 30 seats on the party's central committee.
If the Maktabi are in this advantageous position, why have they held back from forcing parliamentary acceptance now of the blue-print they want for the Khomeini succession?
One possible reason is that they have reservations about the seemliness of an open brawl over the succession while Ayatollah Khomeini is still in power.
Another -- and even more plausible reason -- is that the Maktabi do not have the unanimous support of the six or seven Maraj-e Taklid (or highest leading clerics in strictly theological terms) of Persian Shia Islam. The three Maraj-e Taklid best known outside Iran are Ayatollahs Khomeini, Kazem Shariat-Madari (a Turkish speaking Azerbaijani from Tabriz based in Qom), and Shirazi.
Of the six or seven Maraj-e Taklid, the one posing the biggest threat to Ayatollah Khomeini since the beginning of the revolution has been Ayatollah Shariat-Madari. He was generally recognized as the No. 1 Marja-e Taklid within Iran before Ayatollah Khomeini returned from exile in February 1979. His views on politics have always been close to those of the Hodjatieh -- a group, incidentally, whose roots go back to the early 1970s.
The Maktabi therefore have a vested interest in discrediting Ayatollah Shariat-Madari and removing him as a potential claimant for Ayatollah Khomeini's mantle.
This explains the bizarre plot ''uncovered'' last month in which Ayatollah Shariat-Madari allegedly was privy to a plan whereby former Foreign Minister Sadeq Ghotbzadeh was scheming to assassinate Ayatollah Khomeini.
Since discovery of the ''plot,'' Ayatollah Shariat-Madari -- already under virtual house arrest -- has been formally deprived of his teaching base at Qom and stripped of his title as a Marja-e Taklid. Ayatollah Khomeini endorsed this move. But significantly only two other of the six or seven Maraj-e Taklid have done so.
Where does Army commander Colonel Shirazi fit into all this? If he emerges as the victorious hero over Iraq, as leader of the men with guns, he could render all the interclerical bickering over the succession academic.