TUNIS -- Dominated for 30 years by the force of one man and the political institutions he created in his image, Tunisia is now adjusting to a government headed by a half-dozen strong personalities who are debating with each other over the directions this North African nation should take.

The debate is directed and contained by the new Tunisian president, Zine Abidine Ben Ali, who is in turn adjusting to the paradox that the strongest resistance to his proposals for political change comes from the national political party that he now heads rather than from his regime's declared Islamic and secular opponents.

Ben Ali, 51, took power here Nov. 7, deposing Habib Bourguiba, the elderly and incapacitated founder of modern Tunisia, through constitutional means. He also appointed himself head of the party created by Bourguiba, the Destourian (Constitutional) Socialist party, which is the only political body represented in the country's 125-seat parliament.

By promising to open up the political process and establish a genuine multiparty system, Ben Ali and the political technicians he has brought to the top of the government have created resentment and dismay in the top ranks of the party, which is accustomed to running elections and taking the pick of government jobs as a matter of right.

Opponents who praise Ben Ali for freeing thousands of Tunisians locked up during Bourguiba's final chaotic months in power assert that the clearest test of his commitment to restoring democracy will come in his willingness and ability to confront the party and, if necessary, risk splitting it.

They cite with concern reports of massive electoral fraud in the four Jan. 24 legislative by-elections in which Destourian candidates won by their customary margins.

"We welcome the changes Ben Ali has brought, but we still wait to see if it was only a change of leaders or if it really was a change of regime," said Khemais Chamari, a member of the opposition Movement of Socialist Democrats party and a human rights activist. "The president says he is aware that there were 'excesses,' but we want to know if he has the willingness to do something about it."

In an interview last week, Ben Ali acknowledged that old-guard party leaders were showing "a certain reticence" over the political and press reforms he is pushing. "We will have problems, but not serious ones," he predicted.

Ben Ali is moving toward a party congress this summer that is likely to be decisive in his attempt to put his own stamp on an organization that is thought to have about 500,000 members. He also is expected to advance the elections for a new parliament now due in 1991.

His point man in this effort is his prime minister, Hedi Baccouche, who said in a separate interview that the party now "needs to attract intellectuals, young people and people of all parts of society."

Baccouche, a senior civil servant who held key diplomatic, party and Cabinet posts before being elevated by Ben Ali to prime minister in November, emphasized that the party also would reach out to Islamic moderates, who were anathema to Bourguiba and thus to the party in recent years. "We cannot allow one group to confiscate religion and make it theirs," Baccouche said. "Before Nov. 7 the people had the impression that the government was against Islam. Now they know that the government is as Moslem as are the people. All Tunisians are Moslems. Even the Communist Party here is Moslem."

A law expected to be passed in the next few weeks will permit parties that reflect Islamic philosophy and belief as part of their organizing principles. But limits will be placed on using Islam in the name of a party and on how directly a party can claim to be the unique representative of Islam, Baccouche said.

Baccouche and foreign minister Mahmoud Mestiri, a career diplomat who was most recently Tunisia's ambassador to the United Nations, are portrayed by western diplomats as the driving forces behind many of the liberal reforms that have been enacted or are under consideration by the new government.

They also have played the key roles in implementing a more activist Tunisian foreign policy and particularly the decision to renew ties with Libya. The two countries will eliminate visa requirements for their citizens on March 19, much to the discomfort of U.S. diplomats who fear that Libya's Col. Moammar Gadhafi will find it easier to carry out destabilization and assassination efforts inside Tunisia.

Also uncomfortable with the easing up on Moslem fundamentalists and on Gadhafi is Interior Minister Habib Ammar, who is, like Ben Ali, a U.S.-trained military man and who was head of the powerful national guard at the time of the November takeover.

Ammar publicly defers to the political authorities on these questions, but in private comments he is known to emphasize the need to put elaborate controls in place to filter out any Libyan agents at the border and to watch fundamentalists. The tone in his comments is much closer to that of Ben Ali when he discusses such questions than the more relaxed formulations of Baccouche and Mestiri.

"There seem to be two groups, the security side of the house and the watch-my-footwork side of the house, on these issues," one western diplomat said. "There is no doubt that Ben Ali makes the final decision, however. And he tends to the view that you need to have order before you can have a political dialogue. The reforms will go ahead as long as he doesn't have to choose, but that could change if he runs into trouble."

Ben Ali has instituted an American-style National Security Council to reconcile the different points of view. It now meets every Monday and is thought by diplomatic analysts to be Ben Ali's chosen mechanism to direct the government.