Shahpour Bakhtiar, the former Iranian prime minister who sent the shah into exile and was then turned out of power by Ayatollah Ruhollah Khomeini after little more than a month in office, is preparing for a comeback.

"Khomeini is finished, he cannot last out the winter," Bakhtiar said in an interview in his sparsely furnished apartment in the posh Paris suburb of Neuilly. The only decoration in the living room was a huge topographical map of Iran covering half of one wall.

Bakhtiar said his followers have already been operating a radio station in the Tehran region for two weeks. He displayed copies of a cheaply printed, 16-page Persian-language pamphlet that he said outlines his program. He added that 100,000 copies are about to be distributed in Iran.

Authoritative analysts here say Bakhtiar does seem to be serving as the focal point of contacts among prominent Iranian political exiles, but they say they have difficulty picturing him as the head of a new Iranian government. A longtime opponent of the shah, Bakhtiar originally accepted power from the then besieged ruler, who appointed him to form a civilian government and end the country's civil strife.

The analysts say they do not think anyone in the large Paris exile community is going to have a determining role in post-Khomeini Iran. The next government is likely to be made up of people who stayed in Iran, the experts have concluded. There are thought to be more than 20,000 Iranians in the Paris area, but it is hard to get precise numbers since Iranians do not need visas to enter France.

The exiles give unmistakable signs of smelling a decomposing rule at home. Their attempts to push each other aside in the struggle to return to Tehran have reached a new intensity in the past few weeks as the Islamic republic has lost world sympathy over the continued holding of the hostages in the U.S. Embassy.

The exile leaders seem genuinely convinced that it it no longer a matter of whether Khomeini will be overthrown, but of when and how.

The soft-spoken, 65-year-old Bakhtiar made it clear that he considers himself the only viable alternative, after Khomeini, to the pro-Soviet Communists of Iran's Tudeh Party.

On Sunday, Princess Azzadeh Shafik, niece of the deposed shah, vowed in an interview to mount a counterrevolutionary movement from Paris aimed at installing a younger generation of the imperial family in power in Iran. She bitterly denounced Bakhtiar. The shah's twin sister Princess Ashraf, who is Princess Azzadeh's mother, has herself begun a campaign of advertisements and letter-writing denouncing Khomeini's Iran.

Bakhtiar expressed worry that the Tudeh which has supported Khomeini since his return without public question is already so firmly entrenched that dislodging it may be a major problem. The Tudeh accepted Khomeini's theocratic archaic constitution, Bakhtiar said, because they decided to infiltrate the Islamic republic and take over "when the old man goes."

Apparently for that reason he said he did not make the overthrow of Khomeini a precondition for his own return to Tehran even though he insisted that his personal security must be guaranteed. Bakhtiar indicated that he fears that if he arrives after Khomeini is overthrown it might be too late to prevent the Tudeh Communists from using their present inside position to grab power.

As for non-Soviet Communists like the pro-Palestinian Fedaye and the Islamic Marxist Mujhadeen Bakhtiar said that there are many "very attractive" people among them with whom dialogue is possible. His program incorporates many of their demands, he said.

As for the monarchists, he said that they are "completely negligible." He said he had only met once with Shariar Mustapha Shafik, the 34-year-old nephew of the shah assassinated here Dec. 7.

Bakhtiar dismissed Princess Azzadeh, the dead man's sister, as "unbalanced." She has been accusing the former premier of betrayal. "I think she is very unfair to me" said Bakhtiar. "I said I thought her brother was clean and patriotic and it took a lot of courage to say that in the current climate."

Bakhtiar strongly denied Azzadeh's allegations in the interview Sunday that he had been in the pay of her family's Pahlavi Foundation. "Never in my life did I take a rial from the court," he said. "I owe the Pahlavi family nothing."

While he said he personally favors a democratic republic, a successor government to Khomeini should give the Iranian people the choice between a constitutional monarchy and a republic.

Bakhtiar said that he has been in contact with disaffected military officers, "but to go from there to say that I have given them instructions would be indiscreet."

The "immense majority" of the officers have "an undeniable disgust" for Khomeini, he said. He expressed great respect for the Army and spoke of the need for "an organized force that is larger and better equipped" than the Tudeh "to neutralize" it.

If Khomeini were to fall into his hands, Bakhtiar said he would put him on trial, "with all the national and international legal guarantees," for having executed so many people and for having run the economy into the ground.

Bakhtiar admitted that he is essentially the representative of the Iranian middle class. He expressed an elitist view of its ability to govern. "The leaders of men," he said, "are the intelligentsia -- it is the intellectuals, the political parties with doctrines, the doctors, the lawyers, the technocrats who decide a country's fate."

As for the new Iran's foreign relations, he said, it would not let the West, particularly the United States, repeat the mistakes of the past 25 years, first by supporting the shah, and then Khomeini. "I have told the Americans, 'Gentlemen, forget it.' You'll never have a regime like the one before, or else it will be something worse."