An unexpected challenge has arisen to South African President Pieter Botha's bid to win black support for his strategy of gradual race-policy reforms. The source is the ``Colored'' (mixed-race) Labor Party of the Rev. Allan Hendrickse. Having braved the denunciations of militant community leaders to take part in the first stage of the reform program - the creation, in 1984, of separate chambers for Coloreds and ethnic Indians in the previously all-white legislature - Hendrickse's party is now pressing the President for more concrete pledges to abandon all racial segregation.
In particular, the party demands the repeal of the Group Areas Act, which segregates residential areas. Mr. Botha has hinted at softening its practice, but has ruled out repealing it.
Tension between Mr. Hendrickse and Botha boiled over Monday when the Labor Party leader - one of two nonwhite members of Botha's Cabinet - suddenly quit his post. He was quoted yesterday as suggesting the move would herald generally tougher scrutiny of Botha's reform program in the Colored parliamentary chamber.
In practice, this may have little immediate impact. The so-called ``tricameral'' legislative system still allows Botha's National Party, as the largest white parliamentary faction, to push legislation through despite opposition of the nonwhite chambers.
But there is one exception to this rule: legislation relating to the life span of the elected Parliament. This means Hendrickse's party could block Botha's bid to postpone the next national parliamentary election from 1989 until 1992, or force the President into the embarrassing position of seeking a change in that constitutional provision.
The plan to delay the next election is seen as central to Botha's overall strategy. According to National Party sources, his plan is to strike a careful balance between white fears and black aspirations by retreating little by little from remaining discimination laws. At the same time, Botha hopes to embark on the presumably slow process of convincing credible black leaders to join him in a search for a compromise formula of national power sharing.
The newly rebellious tack by Hendrickse began last year when he joined the Indian parliamentary chamber in attempting to veto tough new security laws aimed at quelling black political unrest. Days later, the Botha government sidestepped this obstacle by incorporating the new security provisions into a declaration of a nationwide state of emergency.
Early this year, Hendrickse staged a defiant protest against continued racial segregation of many public facilities by taking a swim at a ``whites only'' beach. But Botha called him to order, and Hendrickse apologized.
Since then, political analysts here say, Hendrickse's resignation from the Cabinet appeared to be an act merely awaiting a catalyst. That catalyst came last week, when Hendrickse demanded the government tell him what reforms it would move forward if given an additional three-year lease on the present Parliament. When Botha said that such a demand also represented a breach of Cabinet discipline, Hendrickse quit.
It remains to be seen how energetically Hendrickse will follow up his implicit threat to block a delay in elections. He may not relish an early reckoning with a colored electorate that signaled its widespread opposition to the tricameral system by boycotting the 1984 election in large numbers. But at a minimum, the resignation is seen as further complicating the government's priority effort to get black leaders to negotiate.
Journalists in South Africa operate under official press restrictions.