South African President Jacob Zuma is the main mediator of the ongoing political crisis in Zimbabwe, four years after an accord known as the Global Political Agreement (GPA) was signed to ensure reforms and free and fair elections.

A national unity government was set up, but protest organizer Den Moyo says there has been no progress on reforms.

"We are saying Mr. Zuma as we stand here as Zimbabweans, we are calling upon you to use the powers vested in you as the mediator of the GPA in Zimbabwe to ensure that there is a road map to free and fair and indisputable elections," said Moyo.

One stipulation is that there must be constitutional change before the next round of voting. The Africa director at the Wilson Center in Washington, Steve McDonald, says President Mugabe is trying to get re-elected as soon as possible, so he may try to convince South African mediators to change their view on the need for constitutional reform.

"He wants to get beyond the power-sharing arrangement," said McDonald. "He is under pressure from the South Africans who have declared that they will not recognize or work with him if the preparations for the election do not precede it and the main thing there is the constitutional referendum."

At recent celebrations marking 32 years of Zimbabwe's independence and his power, the 88-year-old president called on political parties to go beyond the violence of recent elections.

"We must take absolute care and caution and ensure that the fights of yesterday are buried in the past," said Mugabe.

Mugabe has denied rigging previous elections. He has said he needs to stay in power to correct the wrongs of previous white minority rule and ensure the economic empowerment of Zimbabweans.

Back in Washington, Nyare Joe sang opposition protest songs. She said Zimbabweans inside Zimbabwe are not free to question anything related to Mr. Mugabe or his ZANU-PF party.

"I want everybody even in my country to be able to do anything, once it is a free country," said Joe. "Mugabe - now you cannot talk about the name of Mugabe or you go to jail. You cannot even laugh when ZANU-PF is there, or you go to jail."

The protesters warned if there is not more pressure against President Mugabe, he would remain in power as long as he is still alive, through stalling tactics or rigged and violent elections. 

Efforts to reform the constitution have gone slowly, while no date has been set for the looming presidential and legislative election.