JOHANNESBURG -- As South Africa's apartheid system of racial separation crumbles and its political landscape changes, no group seems more bewildered and divided than white liberals.

To many South Africans, the situation appears filled with irony. While President Frederik W. de Klerk's National Party steps from the ruins of its failed separatist ideology to display flexibility and imagination and to position itself for what it views as the coming of a multiracial political system, the liberal Democratic Party is at cross-purposes about what its role should be now that its ideas have triumphed.

At a convention Aug. 31, the National Party voted unanimously to open its doors to blacks, and its leadership announced that it was preparing to form alliances with black parties in an attempt to remain part of the power structure after majority rule.

In contrast, the Democratic Party, at a convention last weekend, was riven with dissension about whether to link up with the National Party, to seek ties with the African National Congress, South Africa's most prominent black nationalist group, or to go it alone. To avoid a split, the party amended its resolutions and agreed to explore all three possibilities.

The problem facing the Democratic Party -- which received more than 400,000 votes, or 20 percent of nearly 2.2 million ballots cast by white voters in parliamentary elections last September -- is that the transformation of the long-dominant National Party into an integrationist organization has encroached on the Democrats' constituency and taken away the anti-apartheid cause that was the reason for the Democrats' existence.

Now, as they contemplate a future of black liberation that they have campaigned so long to achieve, there are some among them who are eager to join the new wave by linking with the ANC, but others who fear that such a move might represent an abandonment of the Democrats' traditional liberal values because of the ANC's long-standing alliance with the South African Communist Party.

The division has been deep and emotional. It has cut through old friendships, and it produced heated exchanges at the convention. Few observers believe the party can survive long without splitting.

Part of the irony is that those who appear most fearful of the new wave include a small band of idealists, known as "true-blue liberals," who broke from the opposition United Party in 1959 to form the Progressive Party and survived nearly two lean decades before a succession of mergers produced the Democratic Party, which now has 27 legislators in a parliament of 177.

Helen Suzman, who from 1966 to 1974 was the Progressive Party's lone parliamentary delegate, has retired and was not at the convention. But the legislator who now has the seat from her constituency, Tony Leon, emerged as one of the "true-blue liberals."

The new "progressives," on the other hand, contain a high proportion of Afrikaners -- descendants of Dutch, French and German settlers long considered among apartheid's most resolute supporters. These "progressives" consist of converts from the National Party who seem less troubled by the idea that a black-majority government may at times depart from Western liberal values.

As one of them, Jannie Momberg, put it at the convention: "I have never been a true-blue liberal, but I have a conscience that tells me where to go and what to do. Expounding liberal values is not enough. We have to get down to the {black} grass roots and make this thing work."

The differences emerged in a debate on two resolutions, one calling for the party to negotiate a pact with the ANC and the other to work out joint objectives with de Klerk.

Proposing the ANC pact, David Dalling, the party's chief whip, said it would be a logical extension of the Democrats' long campaign against apartheid "to identify with those who have suffered under apartheid rather than those who have imposed it."

Now is a time for national reconciliation, Dalling said, and it would be unfortunate if the Democrats lined up on the side of the National Party against the ANC at the negotiating table. "Such a black-white lineup would be the wrong way to start building a nonracial democracy," he said.

The proposal drew fiery opposition. "A pact with the ANC will be a Warsaw Pact," contended Harry Schwarz, a legislator and longtime associate of Dalling's, in an apparent reference to the ANC's alliance with the Communists.

"I don't want to get together with a party that gets support from {Palestine Liberation Organization Chairman} Yasser Arafat, {Libyan leader Moammar} Gadhafi and {Cuban leader} Fidel Castro," Schwarz added.

For the "true-blue liberals," ensuring that a new South Africa is governed according to what they termed "Western democratic values" appeared of primary concern. They quoted the 17th- and 19th-century British philosophers John Locke and John Stuart Mill, and they expressed doubts whether these values would be safe with the ANC.

The "progressives" argued for realism in facing the fact that "we are moving from the politics of 5 million to the politics of 35 million" -- the increase in the electorate if blacks get the vote. The ANC is a coalition of many different political elements fighting for the common goal of black liberation, they argued, and the Democratic Party should join the coalition to influence it from within.

"Unless we do that we will find ourselves in some little corner with 2.7 percent support," warned Jan van Eck, a "progressive" Afrikaner.

"I find it strange," said Peter Gastrow, a "progressive" legislator from Natal, "that this party, having fought for years for a nonracial democracy, instead of joining and helping to shape it now that it is there, should want to withdraw from it and feel more comfortable with F.W. de Klerk."