Robert Mugabe's regime has been using increasingly violent tactics to prevent any form of protest. With the economy in freefall, unemployment spiralling, real inflation approaching 2,000% and no money to pay the security forces, all public protests have been banned. Life expectancy for women has dropped below 34 and millions of men have crossed the border into South Africa to find work and food. In this situation, the government is determined not to give the opposition any kind of focal point.

Recently there has been a new mood of defiance which culminated in a protest rally at the weekend and the arrest and apparent torture of the opposition leader Morgan Tsvangirai.

So how strong is Mugabe's grip on power?

Twenty-seven years after sweeping to power in the country's first free elections, the man who trained in Ghana to be a schoolteacher is still his country's supreme power. Aged 83, he has a Fidel Castro-like ability to speak for hours without notes and sit through interminable senate sessions without pause. He has divided and ruled since the end of the liberation struggle and seen off every rival. Even those who hate him admit he is an exceptional tactician with extraordinary determination and self-discipline.

However, with each passing year, the remaining threads of legitimacy fall from him. Others now imagine what their role might be after Mugabe.

Will he face a challenge from within the ruling party?

After decades of concentrating wealth and power in their own hands, Zanu-PF leaders are haunted by its possible loss in a succession crisis. As a result, the party has never been so divided. For almost the first time, Mugabe has not been able to impose his will. A proposal to "harmonise" presidential and parliamentary elections - in effect extending his term from 2008 to 2010 - was not backed unanimously. While there are many ambitious lieutenants, the two main contenders for succession are Emmerson Mnangagwa and Joyce Mujuru. Mnangagwa is his favoured candidate, according to sources. He oversaw the massacre of 25,000 Ndebele in the notorious Gukuruhundi campaign of the 1980s. But Mnangagwa, thought to be Zimbabwe's richest politician, faces fraud allegations through the statecontrolled press, fed by Solomon Mujuru, the former army chief and husband of the vice-president, Joyce.

She acquired a fearsome reputation during the war, as well as the nom de guerre 'Spill Blood', and added to that power base during the land invasions.

What neither offer is any cause for optimism over a change in direction.

What about the opposition?

While the country is practically bankrupt, the Central Intelligence Office, (CIO) functioning as Mugabe's secret police, enjoys a budget many times that of the health service.

The CIO has been ruthlessly effective at sowing confusion and mistrust in the opposition camp and credited with forcing a damaging split in the main party, the Movement for Democratic Change (MDC).

After leading his party to two heavily disputed electoral defeats, Tsvangirai now heads a divided MDC, after a fallout over a proposed boycott of senate elections.

The pro-senate wing is led by Arthur Mutambara, an MIT-trained academic who has has drawn support from many in the country through his appearance to be a political novice. Tsvangirai, however, remains the one man with the charisma and public support to rattle the regime. Questions have been asked over his willingness to act after two treason trials left him facing the death penalty and house arrest for years at a time.

The result of this division has been an increasing reliance on broader alliances such as the Save Zimbabwe coalition that called last weekend's rally. These groups, comprised of civil society organisations, religious leaders and trade unions preaching non-violent protest, have proven harder to silence.

For much of the past three years, the Catholic Archbishop of Bulawayo Pius Ncube has been Mugabe's most voluble and bravest critic.

What can other governments do?

Mugabe has easily outmanoeuvred Commonwealth leaders, international organisations and the British royal family alike. He realised early in the economic downturn of the 1990s that a return to the narrative of colonial struggle was the best way to hide the deficiencies of his own regime.

The World Food Programme has been forced to hand over its operations to Zanu control or leave millions to starve. What is needed is a subtle policy of containment and encouragement of neighbouring leaders to use their influence to avert a catastrophe on their own borders.

Also, the arrival of China in African affairs has removed many of the remaining levers of influence in London and Washington. Much of the west's moral capital has been spent in Iraq and its short-sighted foreign policy in Africa itself.