Rajoelina's return could dramatically shake up Madagascar's political landscape, ahead of November's presidential election.
“We certainly have to take it seriously," Paul Melly, Associate Fellow in the Chatham House Africa Programme, told RFI.
He's one of the three men who have dominated Malagasy politics in recent years, explains Melly. The two others are Marc Ravalomanana, who was deposed in a military coup that brought Rajoelina to power in March 2009, and current president Hery Rajaonarimampianina.
"There’s also a practical electoral reason: Rajoelina clearly has a lot of money," he says.
The 44-year old launched his ambitious programme called the Initiative for the Emergence of Madagascar (IEM) at the Petit Palais art gallery in Paris in May.
"Not many Malagasy politicians have the sort of capacity to launch their political agenda in a foreign capital with a high profile event like that," comments Melly.
The young opposition leader may have the campaign capacity, but he also has a lot of expectations riding on his shoulders, notably from the Diaspora.
"I hope that his programme will concern all the country, the rural areas and not just the main cities," Philippe Rajaona, a member of Malagasy civil society, told RFI.
"For the last decade, Madagascar was in a deadlock. Growth was only in the main cities and didn't concern the rural areas; yet we have 22 regions in Madagascar, we need development, we need policies that can bring political change and economic solutions for all," insists Rajaona.
Economy high among voter concerns
Rajoelina, like many of the other candidates, is promising to improve the country’s economy and improve living standards.
The poverty rate stands at almost 92% and has been aggravated by the recent drought and floods, which have destroyed more than 70% of crops.
"The population outside the capital is living in a situation of despair," says Emmanuel Dupuy, president of the Institute for European Prospective and Security Studies (IPSE).
While the incumbent President Hery Rajaonarimampianina has promised an ambitious economic programme called "Emergence 2030", Dupuy says there is a "hiatus between the economic situation now and how he is wanting to push it in the far future."
For Melly however, Madagascar's economic problems stem from the period in which Rajoelina led the country. "The big criticism of him is not what happened when he was installed," but the aftermath.
The opposition leader came to power through a putsch in March 2009.
"A transition that could have been sorted in 9 months or a year, and allowed Madagascar to return to status quo, instead lasted four years, mainly because he [Rajoelina] wanted to be a candidate," explains Melly.
"And all this time the country had no constitutional government and aid was suspended and the economy was shrinking and investors fled."
President Rajaonarimampianina at least has brought investors back, acknowledges Dupuy. Yet he's struggled to maintain a stable parliamentary majority and in May faced social protests after his attempts to change the country's electoral laws to block Rajoelina and Ravalomanane from running in the November election.
President under pressure
The president is "under pressure from the opposition and even within his own party from those MPs who contested his electoral laws," says Dupuy.
The constitutional court ruled on 3 May that parts of the electoral law, including those that would have prevented Ravalomanana and Rajoelina from running, unconstitutional, weakening the president further.
"He has tried to have a defensive policy in the last two months in nominating a consensus government but that seems to be not enough," adds Dupuy.
Rajaonarimampianina entered into a union government in June with Prime minister Christian Ntsay, an ally of Rajoelina, to quell the May protests.
But Rajoelina's "possible declaration will put the president under more pressure," reckons Dupuy.
The first round of the presidential election will take place on 7 November. It may go into a run-off in December if none of the candidates obtain 50% of the vote.
The temptation for whoever comes third will be to strike a deal in the hope of securing a share of influence.
“Whether any of them can cut a deal with any of the others, and how far any of them would be prepared to compromise is difficult to say," comments Melly.
"We have three people, each of whom is pursuing a very personalized agenda and who’ve all been prepared to push the bounds of constitutional and legal means to pursue their own ambitions for the top job."
Candidates have until 21 August to submit their applications.