The growing calls for elections to end the "failed" Government of National Unity (GNU) and the eerie silence on its third anniversary serves as a barometer that the unity government may well be preparing for its swan song.

The Sunday Times assesses here the three principals in the coalition government to gauge the biggest winners and losers in the three-year-old unity government, that has often been ridiculed within political circles for being a "marriage of inconvenience", and "a government of no unity".

PRESIDENT ROBERT MUGABE, 87

Mugabe has undoubtedly used the GNU to strengthen his position after his shock defeat by Tsvangirai in the March 2008 elections.

The GNU, initially seen as a "gentleman's arrangement", in which the veteran leader could not be left out in the political wilderness, was given the privilege to lead the GNU as the political leaders set out to find a lasting solution to the 10 year-old political crisis.

But it afforded Mugabe, a maverick tactician who had his eyes set on a looming election, to strengthen his position - scooping key "power" ministries for his Zanu-PF party, rebuffing consultations with Tsvangirai and rolling out a string of unilateral appointments of governors, ambassadors, security chiefs and the central bank governor, Gideon Gono.

No GNU meetings are held without Mugabe, and all cabinet meetings have been chaired by the 87-year-old leader, although provisions in the GNU allow that the chairmanship be rotated between Tsvangirai and himself.

Mugabe has often reminded his Zanu-PF members not to get cosy with the GNU - and said it was "temporary", with the next challenge to win the elections.

But Mugabe's old age, strong speculation of ill-health and factionalism in his Zanu-PF party are seen as the biggest threat to his political run, rather than pressure from the Southern African Development Community (SADC) and Tsvangirai crying foul over his grip on power.

PRIME MINISTER MORGAN TSVANGIRAI, 59

Tsvangirai has had a bitter-sweet spell in the GNU. His Movement for Democratic Change (MDC) party managed to stop the free fall of the economy, bringing relief to ordinary Zimbabweans weighed down by food shortages and hyperinflation.

The MDC's point-man, Tendai Biti, who is the Finance Minister, has in the past three years watched over a recovering economy - good news for business and foreign investors.

But if restoring Zimbabwe's economic shine under the GNU has proved to be a boost for Tsvangirai's credentials, a look at the political state of affairs tells a very different story.

Tsvangirai's repeated attempts to rein in Mugabe have failed, and in consequence projected him as weak.

Questions are being asked within political circles of Tsvangirai's ability to challenge Mugabe and provide strategic leadership, given his perceived over-reliance on the SADC at each turn of Zanu-PF belligerence.

Politically motivated violence, farm invasions and slow media and political reforms have weighed down heavily on Tsvangirai - with the latest re-appointment by Mugabe of military service chiefs dealing a blow to the MDC strongman.

Coupled with his gay rights gaffe and sexual escapades, which were capped by his controversial 12-day marriage to Locadia Karimatsenga last year, analysts say Tsvangirai's political shine is coming off and warn of waning public perception over his leadership qualities.

DEPUTY PRIME MINISTER ARTHUR MUTAMBARA, 45

Mutambara's place in the unity government was the source of criticism from the onset and it set tongues wagging within the political landscape.

As a "newcomer" to Zimbabwe politics, the 10-year-long fight between Mugabe and Tsvangirai was always likely to place Mutambara in the shadows.

The loss of his presidency of the splinter MDC party to Welshman Ncube last year sealed his fate as an "irrelevant" political figure in the GNU.

The end of the GNU is likely to hurt Mutambara the most, as he faces isolation since he now does not lead any party, unlike his other partners in the GNU.

Political analyst Alexander Rusero says: "Mutambara was lucky to have been considered in the GPA arrangement, because the smaller faction of the MDC is a club of political grasshoppers that never attempted to contest for the presidency."