Zimbabwe's opposition party feels abandoned with its leader in exile

Zimbabwe's opposition ZAPU party appears to be a badly rattled and demoralized political machine. The party of Joshua Nkomo - whose legendary struggle for independence helped to bring about that status in 1979 - wants a ''merger'' with arch-rival ZANU-PF, according to ZAPU deputy chief Josiah Chinamano.

But recent statements by Mr. Nkomo, still leader of ZAPU, reportedly are blocking progress toward such a merger. Nkomo has accused ZANU-PF's leader, Prime Minister Robert Mugabe, of ordering government security forces to kill him (a charge Mugabe vehemently denies).

The ZAPU (Zimbabwe African People's Union) chief fled to Botswana March 9 and is now in London. If Nkomo hoped for some political gain by going into exile, that mission is regarded as having failed. No government seems prepared to grant him asylum. His own party wants him to return home.

Last week Chinamano, who took over as acting ZAPU leader, reaffirmed his own desire for an early merger with the ruling ZANU-PF (Zimbabwe African National Union-Patriotic Front). And he publicly stated that he is ''gratified'' that Prime Minister Mugabe has guaranteed Nkomo's safety if the ZAPU leader should return home.

The seemingly conflicting statements of Nkomo and Chinamano raise all sorts of questions about ZAPU's - and Zimbabwe's - political future.

Chinamano says he supports the concept of a one-party state - and the sooner there is a ZANU-ZAPU merger, the better. (Mugabe and, at least in theory, Nkomo both support the idea of a one-party state.)

In at least two major public statements Chinamano has made since Mr. Nkomo's departure there is little evidence of sympathy for the ZAPU leader's behavior. Chinamano has said Nkomo is ''badly needed'' in Zimbabwe, not London.

ZAPU would seem to face three choices:

* It can press for the best possible ''merger'' terms that it can get. But with ZANU clearly in the ascendant, and with government ministers claiming that thousands of ZAPU supporters have defected to ZANU even in Nkomo's political base of Matabeleland, the ''merger'' is likely to turn into a ''takeover.''

* It can fight on as an opposition party. This is an unattractive prospect given the party's minority position in the country.

* It can resort to ''armed struggle.'' This appears to be the option that 600 or so dissidents have already adopted. This, too, looks to be an unpromising option given the Ndebeles' limited numbers and lack of supply and logistical support. They could seek aid from South Africa, but this seems unlikely.

All of this makes pretty gloomy reading for ZAPU.

There is another side to the coin though, and that is the aftereffects of the campaign by the security forces in Matabeleland against the dissidents.

In the view of some Western journalists and aid organizations, some of the tactics used are likely to have created long-lasting bitterness and antagonism, which raises the question of whether the mild-mannered and moderate Josiah Chinamano or even the older and tired Joshua Nkomo are likely any longer to reflect the views of the militants.