Iran's Guardian Council on Thursday disqualified former president Mahmoud Ahmadinejad from the country's May 19 presidential elections.
The government's vetting body approved six other candidates including the incumbent President Hassan Rouhani.
Ahmadinejad, who ruled from 2005 to 2013, was barred along with his close ally Hamid Baghaie.
Ahmadinejad shocked everyone by registering as a candidate last week against the advice of Supreme Leader Ayatollah Ali Khamenei -- a move which many described as political suicide.
According to the state media, the other candidates selected were hardliners Ebrahim Raisi and Mostafa Mirsalim, Tehran mayor Mohammad Bagher Ghalibaf, moderate Mostafa Hashemitaba and Rouhani's ally and vice-president Eshaq Jahangiri.
TRT World spoke to Tehran-based journalist Amin Darban.
Khamenei appoints half of the members of the Guardian Council.
By disqualifying Ahmadinejad, the body runs the risk of being seen as a rubber stamp for the supreme leader, who is the highest authority in the country.
More than 1,600 candidates registered to run in the May 19 election, but the Guardian Council only ever selects around half a dozen.
More than 130 women registered but not one has ever been allowed to stand.
"In Iran, it's not only an election, it's also a selection," said Clement Therme, Iran research fellow for the International Institute for Strategic Studies.
Although campaigning was not due to start until April 28, the Guardian Council announced that it could begin immediately.
The approval of Rouhani, a moderate and Raisi, a political hardliner thought to have the backing of Khamenei, sets up a showdown between rival political camps.
Rouhani and Raisi will likely face off over the economy as well as the nuclear deal signed with Western powers.
Rouhani has been highlighting the nuclear deal as his signature achievement during the past four years in office.
Iran agreed to curb portions of its nuclear program in exchange for the lifting of several sanctions as part of the deal.
Political hardliners see the deal as a form of capitulation and are wary of the opening it presents for Western companies to work in the Islamic Republic.