Writing in her weekly online newsletter on Friday, Zille said there had recently been signs of a change from the past few years, when any critical or challenging voices had been effectively silenced through various measures.

Lately a series of prominent party leaders had spoken out publicly on issues of conscience.

"In a political climate marked by intolerance and enforced conformity within the ANC, this is a positive development.

"In fact, the belated upsurge in dissenting voices from within the governing party highlights how abnormal our political culture has been for far too long.

"The lack of open debate has affected the quality of our democracy, replacing a diversity of opinion with the sham silence of assent imposed from the top," Zille said.

Now, disagreements between key government office-bearers on topics as various and urgent as Zimbabwe, HIV/Aids and the arms deal pointed to growing impatience with the iron grip the Presidency had placed on the governing party.

"The new mood of public dissent comes, of course, in the context of the continuing bitter succession battle in the governing party."

It had now permeated Cabinet, as well as highlighted a clash of policy between the ANC in government and in Parliament.

Such public disagreements would have been unimaginable a year ago.

There could be no doubt that the right to dissent was being asserted both inside and out of the ANC, she said.

In the run-up to the ANC's national conference in Polokwane in December, the enforced facade of unity was being jettisoned in favour of some kind of debate.
This presented a small window of opportunity for all outside the governing party who cared about the open society which should define democracy.

It did not happen before, because the ANC, like the old National Party, had insisted on a political culture based on fear and conformity to party bosses.

With potentially independent voices constrained, President Thabo Mbeki had been able to insist that it was not ANC tradition to express personal ambition.

"The worse aspect of the succession battle currently raging within the ANC has been the abuse of state institutions to further partisan political agendas," she said.

Now, if the uncertainty and fear that surrounded the succession race had at least one positive spin-off, it was that dissenting opinions were being publicly heard.

This was a positive healthy development. But the divergent views emerging could also be incompatible within a single party for much longer.

There were those within the ANC who still cherished the vision of an open society, where political divergence was reflected through real debate and dialogue, rather than smear campaigns.

"The growing evidence of the ANC's internal debate is the first indication of a gathering momentum towards a realignment of South African politics.

"May this momentum accelerate. It is already long overdue," Zille said.