Nkomo returns to Zimbabwe, but not as the power broker his followers expected

Zimbabwe opposition leader Joshua Nkomo's return to Zimbabwe was not what his supporters expected. Many believed the ''father of Zimbabwe,'' who went into self-imposed exile last March, would make a splashy return and announce a master plan to ease tribal and political tensions.

But when the chief opponent of this country's left-leaning government went to Parliament last week, he wound up debating his ''exile'' in London rather than advancing his party as a viable alternative to that of Prime Minister Robert Mugabe.

Compared with a cool, confident Mugabe, Nkomo cut an uncon-vincing figure, political ananlysts say.

Most observers say Nkomo faces two main problems in returning:

1. He has to rebuild his demoralized party, the Zimbabwe African People's Union (ZAPU).

2. He must decide whether to enter into serious ''unity'' talks with Mugabe's Zimbabwe African National Union-Patriotic Front (ZANU-PF) - or whether to oppose ZANU in the first post-independence elections, likely to be held toward the end of next year.

ZAPU itself is deeply divided. There are the Nkomo loyalists, who are almost certainly the bulk of those at both the party-membership and grass-roots levels. There is also a group of senior party members, including four Cabinet ministers, who have opted to work with Mugabe in some sort of unity coalition.

And there are the dissidents - younger, militant former members of the military wing of the party - who have resorted to force in Matabeleland. This last group has been publicly disowned by Nkomo and the party leadership.

Nkomo's strength is his popularity with the Ndebele-speakers, about one-fifth of Zimbabwe's 8 million people. He is also strong because there is no obvious ZAPU successor.

The name most often mentioned as successor to Nkomo is Dumiso Dabengwa, the intelligence chief of the party's military wing during the nation's independence war. Mr. Dabengwa was arrested and charged with treason last year. He was acquitted - but later detained again.

All this rules him out of the leadership stakes, but his detention at a time that Nkomo is free suggests the government may see him as the more serious threat.

Most analysts think the proposed ''unity talks'' will not produce any clear understanding between the parties. Nkomo's minority ZAPU favors an alliance between the groups, but Mugabe wants a merger of parties. Some ZAPU leaders fear their interests would be submerged in any such merger.

Above all, there are few reasons why Mugabe needs to compromise. He is ahead now. And he has a built-in advantage at the polls: His largely Shona-speaking followers are some 80 percent of voters. Nkomo's Ndebele-speakers account for 20 percent.

If Nkomo decides that his best option is to oppose ZANU in elections - a decision many analysts expect - ZAPU is unlikely to better its 1980 election showing, when it won one-quarter of the seats reserved for black voters.

Such a result might have serious implications for the country. It would further confirm a regional and tribal split in Zimbabwe, leave Mugabe with a comfortable majority, and almost certainly convince active ZAPU politicians to work out a deal with ZANU.

Some suggest unity talks will succeed only after ZAPU has gone to the polls and been beaten. A key question in such a scenario is whether the young ZAPU militants would heed the election results.