Zimbabwean opposition leader Morgan Tsvangirai says he doubts the ability of the ruling party to solve the country's challenges amid efforts to oust President Robert Mugabe.

Tsvangirai says on his party's website Monday that the ruling ZANU-PF party has been hurt by factional battles and that it appears to have differences with the military over how to handle the confusing situation. Mugabe has defied calls to resign immediately. The ruling party is discussing impeachment.

The opposition leader says the upheaval could undermine the opportunity for a "fresh start" after moves by the military and others against Mugabe. "It would be inimical to progress and the future of the country if all this action was about power retention at all costs," Tsvangirai says.

He adds that elections scheduled for next year should be internationally supervised as a way to ensure political legitimacy.