One of the most influential critics of Iran's plans to adopt a new constitution indicated his willingness today to compromise with Ayatollah Ruhollah Khomeini on a major difference between them.

Ayatollah Kazem Shariatmadari's change of position on the issue of the ratification method for the new Islamic constitution came as Khomeini prepared to meet tonight in Qom with the moderate religious leader and two close associates.

Shariatmadari's apparent willingness to compromise on the ratification issue deprives secular political organizations of their most powerful ally in resisting and amending a constitution that they feel offers insufficient guarantees of a democratic government.

Khomeini's talks tonight were with Shariatmadari and Ayatollahs Mohammed Reza Golpayegani and Shahboudin Najafi Marashi.

The meeting followed two weeks in which Shariatmadari had spoken out strongly against the government's proposals to submit the draft constitution to the scrutiny of a 75-member "council of examiners" instead of a larger constituent assembly as previously promised.

His position had found wide support with moderate and left-wing organizations demanding a greater role in the preparation of the constitution before it is put to a yes-or-no referendum.

Earlier this month, Shariatmadari threatened to boycott the referendum if the constitution did not first receive the approval of a constituent assembly.

But today, he indicated in a statement broadcast by Iran Radio that the council of examiners would be an adequate substitute "if the 75 people are experts and honest."

If the constitution received their approval, he said, it would then be official and "there would be no objection to holding a referendum to further strengthen it."

His turnaround on this issue comes after a week in which blistering attacks by Khomeini against critics of the constitution left little scope for continuing opposition without provoking a head-on confrontation with the leader of the revolution.

In his latest attack, Khomeini branded all opponents of the constitution as "communists."

The increasingly intolerant tone of his comments was seen by many as a sign of nervousness at the widening breach among religious leaders over the constitution.

As religious leaders attempted to find a common front on the constitution, there was mixed reaction elsewhere in the country.

An unequivocal statement of support for the constitution came from Karim Sanjabi, leader of the National Front group of parties, who described the draft as "progressive and clearly written by experts."

Sanjabi is believed to have had a part in preparing some of the constitution's clauses, But his support will have only marginal impact at a time when the National Front has been gravely weakened by internal disputes and defections.*