Two broad new political groups are emerging in Indonesia with substantial middle-class support. One is Islamic, the other secular. In a country with a population of more than 200 million in which Christian, Hindu, Buddhist, Taoist and other minorities coexist with a Muslim majority, religion provides an important cleavage line in politics.

Amien Rais heads the Islamic group. Its most surprising aspect is that it now fully backs the government of President B.J. Habibie. Mr. Rais has gone from being a courageous and outspoken opponent of the Suharto regime to being the strongest supporter of its successor.

Is Mr. Habibie then the democrat that President Suharto was not? Hardly, when half of his cabinet was retained from the last Suharto cabinet. There is real talent among them, but they have by no means disavowed the past.

Why has Mr. Rais, the democrat, thrown his weight behind Mr. Habibie? Because Mr. Habibie, former head of the Indonesian Muslim Intellectuals' Association, is seen as an Islamic president.

Suddenly prominent among the emerging Islamic group is KISDI, the Indonesian Committee for Islamic World Solidarity, led by Achmad Sumar-gono. For several years KISDI and its associated Dewan Dakwah missionary organization have been vociferous but marginal. KISDI has organized demonstrations on issues such as Western pornography and gambling, but also on causes that to the outsider appear anti-Semitic, anti-Chinese and intolerant of other religions, including the Javanese mystical religion.

When Mr. Rais addressed a recent meeting in Jakarta that included 10,000 representatives from 44 Islamic groups, he urged people to cease attacking Mr. Habibie's government and give it time to show what it could do. Other speakers promoted the idea of an Islamic political party. KISDI's Mr. Sumargono yelled out, evidently to the approval of those present: ''Islam yes, Islamic party yes.''

The secular group is clustered around Emil Salim and Nurcholish Madjid. Mr. Emil is a former cabinet minister who stands for market-oriented reform. Mr. Madjid is an Islamic intellectual of the tolerant kind who has long said, by contrast to Mr. Sumargono, ''Islam yes, Islamic party no.''

The secular group initially placed itself in opposition to the Habibie government. But it recently toned down its opposition and renamed itself the Counterweight Group, presumably because it does not want to alienate itself from Mr. Habibie by being overly confrontational.

Why has this secular group softened from being an opposition force to one that is merely a corrective to the Habibie administration? There are two reasons. One stems from a remark by Mr. Madjid that Mr. Habibie is now seen by many in Indonesia as an Islamic president.

If moves were made to unseat him, which would in fact not be difficult to do, then his Islamic supporters would not only defend themselves, they would attack, Mr. Madjid warned.

That in turn, he fears, would trigger a possibly bloody takeover by the army, which is determined to block moves to replace Indonesia's secular state with an Islamic regime.

The other reason has to do with Mr. Salim's links to economic policymakers. Many economists and senior officials plead for concerted action and national cohesion to stabilize the rupiah. The powerful commander of the armed forces, General Wiranto, also wants priority given to economic recovery. The military dreads the prospect of 18 months of free-for-all politics.

Confident of support from Mr. Rais, Mr. Habibie has moved to embrace the secular group by coopting several leading technocrats into an important economic advisory council.

If these are to remain the two main political groups in post-Suharto Indonesia, it is likely that Mr. Habibie will stay in office for some time yet.

Gerry van Klinken, editor, 'Inside Indonesia' magazine.