More than 20 presidential hopefuls are contesting the poll, but Chamisa and Mnangagwa are front runners.
Both men have been at the helm of their parties for several months and while they are eyeing the biggest seat in the country, their ascension has sharply divided their organisations.
Mnangagwa’s rise to the presidency of the ruling Zanu-PF as the party’s first new leader since 1975 came after a military coup helped depose Robert Mugabe from power.
He had led the country with an iron fist since attaining independence from Britain in 1980.
Mugabe’s demise came amid him and a faction of the Zanu-PF positioning his controversial wife, Grace, to succeed him.
Mugabe, Grace and a Zanu-PF faction widely known as the Generation 40, or “G40”, lost out after the military elbowed the dictator out of contention last November.
Zimbabwe Defence Forces commander Constantino Guveya Nyikadzino Chiwenga, the brains behind the military intervention, is now Mnangagwa’s co-deputy. Mnangagwa’s second co-deputy president, Kembo Mohadi, comes from another liberation movement - Patriotic Front Zimbabwe African People’s Union (PF-Zapu) - following a unity accord signed in 1987.
What has followed is a purge of officials aligned to Mugabe’s faction.
On the other hand, Zanu-PF’s fiercest rival, the Movement of Democratic Change (MDC) Alliance, will for the first time since its formation in 1999 be participating in today’s elections without its founding leader, Morgan Tsvangirai, who died in February in South Africa after battling colorectal cancer.
His death triggered a brutal battle to succeed him.
As the nation mourned arguably the most prominent opposition leader since independence, a tactful Chamisa unconstitutionally grabbed power ahead of Tsvangirai’s deputy, Thokozani Khupe.
Chamisa and Khupe were, alongside Elias Mudzuri, Tsvangirai’s deputies.
While Khupe was elected at congress, the other two were appointees, hence she was odds-on favourite to succeed Tsvangirai.
The divisions have threatened the existence of the opposition movement.
Like his long-time rival Mugabe, Tsvangirai remained at the helm despite numerous calls for party renewal.
While the youthful Chamisa, 40, might be fancying his chances, with a huge following among the youth disillusioned by economic malaise, history has taught us African liberation movements are a hard nut to crack.
Liberation movements will never easily let go of power. They are determined to retain power by hook or crook.
A scenario still afresh in millions of Zimbabweans’ minds and globally is when Tsvangirai handed Mugabe his first defeat, only for electoral authorities to doctor the results and reduce the landslide victory.
This culminated a rerun, which Tsvangirai boycotted as the military and pro-Mugabe militia unleashed an orgy of violence that left scores of supporters dead.
Short of legitimacy, regional leaders forced Mugabe into a unity sharing government with him as the head of state, military and government while Tsvangirai became prime minister and his party was relegated to less effective portfolios.
Another run-off cannot be ruled out if no candidate receives more than 50% of the vote. A run-off could be held on September 8.
Zimbabwe’s political terrain is a bit tricky and completely different from the rest of the Southern African Development Community in that it has been excessively militarised.
Military generals have infamously declared in previous polls they would never endorse a leader without liberation war credentials.
Mnangagwa’s rebranding strategy has seen some neutrals immediately embrace him as the Messiah.
Mnanangagwa has also seized the opportunity to preach peace, reconciliation, championed the “Zimbabwe is open for business” mantra and reformed the indigenisation economic policies that obstructed inflow of investment into the country.
Those political activists sitting on the fence have been influenced to back the experienced politician Mnangagwa and Zanu-PF.
It will be no surprise if Mnangagwa wins the polls.
However, it remains to be seen whether his strongly speaking against corruption but failing to prosecute well-known corrupt government ministers might work against his chances.
Another scenario is that, even if Chamisa wins the poll, he would find governing impossible.
If Chamisa and the MDC Alliance emerge victorious, the military would make Chamisa’s government highly unsustainable.
As all government ministries and departments in Zimbabwe are heavily militarised, the first five years in power for Chamisa would not be rosy as he will have a tough task to demobilise, disband, decommission and discharge the aspect of militarisation in government.
War veterans have been deployed right from the Grain Marketing Board, the Zimbabwe Republic Police and the Central Intelligence Organisation to the military itself.
This is where Chamisa and his new government would be frustrated into hopelessness. Disappointed former freedom fighters in these institutions would throw spanners into the works through disobedience.
The third scenario is that the military would outrightly reject a victory for the opposition candidate.
Following the removal of Mugabe from power decades after the failure of the opposition for 38 years, the military top brass do not look likely to hand the opposition power on a silver platter.
It is incomprehensible Chiwenga, retired air force commander Perence Chiri (now Minister of Lands and Agriculture), retired general Sibusiso Sibanda (Foreign Affairs Minister) and army chief of staff retired major-general Engelbert Rugeje (now Zanu-PF political commissar) would not allow any opposition enjoy the fruits while they watch.
The military, who have since captured the Zimbabwe Electoral Commission (ZEC), might also influence the election outcome.
The opposition has raised vote rigging concerns ahead of the poll.
The fears are not far from genuine and the beleaguered ZEC might doctor the results in favour of Mnangagwa and Zanu-PF. The presence of regional and international observers would only be a smokescreen of democratic elections.
MDC will again dispute the outcome, but the observers would go ahead to endorse the polls as credible, free and fair.
Any aftermath chaos, protest marches and demonstrations will be referred to the election courts and the verdict will take a lifetime to be declared.
However, investors will be closely monitoring for an enabling business environment, a factor which may entice them to pour their promised $16 billion (R210bn) into the incumbent administration’s coffers.
Amid such a scenario, the world’s second’s largest economy, China, will be the happiest to continue plundering Zimbabwe’s vast mineral wealth.
* Savious Kwinika is editor-in-chief of the Pan African news agency Centre for African Journalists (CAJ News), based in Joburg.
** The views expressed here are not necessarily those of Independent Newspapers.