South African right-wingers desert prime minister

South Africa seems set for the biggest political shake-up it has experienced since the National Party came to power more than 30 years ago.

A long-simmering revolt has finally erupted among right-wingers in the ruling National Party in South Africa that could have a profound effect on the country's future.

After bitter wrangling in a closed meeting of 123 of the party's 142 members of Parliament in Cape Town Feb. 24, 22 finally voted against a motion of confidence in Prime Minister Pieter W. Botha, indicating openly for the first time what many of them have been whispering for a long time: that they think his race policies are too liberal.

It is most unlikely that the leadership will be able to restore the unity of the National Party. In fact, it seems much more likely that there could now be a major cleavage which could shatter traditional South African political patterns, perhaps even smashing in the process the mighty Afrikaner Nationalist juggernaut that has dominated white politics for so long.

Whatever happens, Prime Minister Botha is set for a rough ride. In the eyes of many Afrikaners he has committed a cardinal sin by allowing this serious split in the National Party, thus endangering the party's Afrikaner power base.

On the other hand, more liberal Nationalists have long believed that unless the National Party shucked off its right wing it would never be able to introduce the race reforms they believe are essential and which they believe Mr. Botha himself is impatient to bring about. With the right-wing rebels now apparently out of the way, they will expect him to set about this task with a vengeance.

If he does not, of course, and if he continues with the virtual moratorium on meaningful change that has characterized his administration so far, either they will move to replace him, or they themselves will be tempted to opt out, and vote for the Progressive Federal Party led by a vigorous and forthright Afrikaner, Dr. Frederik van Zyl Slabbert.

Dr. Slabbert and his party seem set to gain immediate political advantage from the National Party's split. The two parties are presently engaged in a bitter contest for control of the city council of the country's biggest city, Johannesburg, and the Progressives seem almost certain to win this now in the poll to be held next week.

Also, if the split in the National Party becomes as convulsive as some believe it might, many Afrikaners who vote for the National Party out of loyalty but not out of conviction might switch to the Progressives.

In Parliament, there is already frantic counting of heads. If the 22 members who voted against the prime minister can gain just a few more supporters, they could even wind up becoming the official opposition in Parliament. To do this, they need to have more than 27 votes - the number of seats controlled by the present official opposition, the Progressive Federal Party.

Minutes before the caucus vote was taken showing 22 rebellious National Party members, a senior Cabinet minister, Dr. Andries Treurnicht, avoided a showdown with his leader by leaving the meeting without voting for or against him. Dr. Treurnicht, known as ''Doctor No'' because of the way he has always obstructed any liberalizing of government race policies, is regarded as the ring leader of the National Party's conservatives. He is particularly powerful because he is the leader of the party in the Transvaal province, which has more seats in Parliament than any other of the country's four provinces.

As the meeting broke up, another Transvaal member of Parliament, Koos van der Merwe, burst out of the caucus room and shouted to newsmen: ''I am finished with Pieter Botha.''

Mr. Botha himself was still visibly shaken by the confrontation in the caucus when he called a brief press conference soon after. He indicated that he regarded the 22 men who had voted against a motion of full confidence in him as being now outside the National Party. But he did say he would give them time to reconsider their position, and that they could still be welcomed back into the party if they changed their stance.

Meanwhile Dr. Treurnicht had a hasty meeting with several of the rebels in his own office, saying he would make his own standpoint clearer in due course.

But already a process of polarization is far advanced within the party.