Iran's former hardline president Mahmud Ahmadinejad took the surprise move on Wednesday of registering for next month's presidential election.
Ahmadinejad had previously said he would not stand after being advised not to by supreme leader Ayatollah Ali Khamenei, saying he would instead support his former deputy Hamid Baghaie who also registered on Wednesday.
He told reporters he remained committed to his "moral promise" to Khamenei of not running for the May 19 election.
Khamenei's "advice was not a ban," he said at the interior ministry where registration was taking place.
"I repeat that I am committed to my moral promise (of not running) and my presence and registration is only to support Mr Baghaie."