Zimbabwe's Ruling Party Bars Vice President From a Top Panel LONDON - A power struggle over who will succeed President Robert G. Mugabe of Zimbabwe seemed to sharpen on Wednesday when the state news media reported that the country's vice president, once seen as his heir apparent, had been disqualified from a crucial panel of the governing ZANU-PF party because she had plotted to have Mr. Mugabe assassinated. The vice president, Joice Mujuru, a party veteran and guerrilla fighter in Zimbabwe's war for independence in the 1970s, has publicly denied accusations of involvement in the purported plot to kill Mr. Mugabe, the 90-year-old autocrat who has been in power since the end of British colonial rule in 1980. The Herald, a government-run newspaper, reported on Wednesday that provincial officials in Ms. Mujuru's home district, Mount Darwin, refused to accept her application to participate in party elections at a congress early next month that is expected to parcel out top positions. The development represented a further setback for Ms. Mujuru, who is in an increasingly fierce struggle for influence in the country with Mr. Mugabe's wife, Grace Mugabe, and Emmerson Mnangagwa, a longstanding rival and former spymaster. The political maneuvering added to the uncertainty in a stretch of central Africa. A power struggle is also underway in Zambia, Zimbabwe's northern neighbor, after the death of President Michael Sata in October. Ms. Mugabe has emerged in recent months as a challenger to Ms. Mujuru, and she has hinted that she has presidential aspirations. Mr. Mugabe, Africa's oldest leader, says that he is in good health and has given no indication that he is preparing to step down. Regarding Ms. Mujuru, The Herald said provincial officials "rejected her application in elections that saw a number of other ZANU-PF bigwigs linked to her nefarious activities to oust President Mugabe also failing to make it." The report followed earlier indications of a purge in Zimbabwe's provinces to remove perceived rivals before the ZANU-PF congress, scheduled for next week, which is seen as likely to endorse Mr. Mugabe once again as the party leader and thus as its presidential candidate. Political analysts in Zimbabwe have said that Mr. Mugabe may be choreographing the political turmoil. Last weekend, according to news reports, the Zimbabwean leader ordered changes in ZANU-PF rules to permit him to appoint his two deputies and to indicate a successor. He has not said publicly who he believes should succeed him. The party's constitution also permits Mr. Mugabe to appoint 10 people to the 245-person central committee that chooses the powerful Politburo, ZANU-PF's executive body. The Herald quoted Wonder Mashange, a senior provincial official, as saying that ZANU-PF leaders in Mount Darwin "agreed that we should defend our president" against "any member of the party who is accused of plotting to assassinate the president." There was no immediate response from Ms. Mujuru. But opposition newspapers quoted her supporters as saying that she had refused to submit her application to the provincial authorities because of the likelihood that it would be rejected. The Herald also reported that senior party members who had been barred from the election had instigated violent disturbances in Harare, the capital, to protest their exclusion. It did not give details.