Mehdi Bazargan, a balding political veteran with a white goatee, was a natural choice for the tough assignment handed him by Ayatollah Ruhollah Khomeini.

At 73, he has a long record of participation in Iranian politics: as a colleague of Prime Minister Shahpour Bakhtiar in the 1950s, through anti-shah agitation in the 1960s and 1970s, to nimble negotiations with striking oil workers on behalf of Khomeini only last month.

Bazargan is known as a devout Moslem -- he has a bump on the forehead from touching his prayer stone -- but also as a moderate eager to reconcile the teachings of the Koran with the demands of the 20th century.

This flexibility has served him well in politics. He has a reputation of openness to dialogue that is likely to serve him well in the days ahead. At the same time, he has retained close contacts with the bazaar traders and conservative Moslem clergy.

Perhaps most important, he has avoided public statements committing him to a single policy in the maneuvering with Bakhtiar.

Bazargan comes from a prominent merchant family from Tabriz in northern Iran. Reza Shah, the father of Shah Mohammad Reza Pahlavi, picked him for a state scholarship in the 1920s and he went to France for study.

After studying thermodynamics and textile engineering in France, he returned for a teaching job at Tehran University's technical college.

Under prime minister Mohammed Mossadegh, he became under secretary of state for education and then managing director of the National Iranian Oil Co. during the troubled days immediately after Mossadegh removed the British.

With the shah's return to power in 1953, Bazargan and his allies were pushed into obscurity. But whenever possible, he continued opposition to the shah, including participation in the 1977 founding of the Iranian Committee for Human Rights. The political work cost him his job at the university one time and four jail terms at other times over the years.

It seemed logical, therefore, that Bazargan turned up at Neauphle-le Chateau outside Paris when Khomeini set up his exile headquarters there.