Former Iranian President Mahmoud Ahmadinejad, in a surprise move, has registered as a candidate for next month's presidential election. He had previously said he would not run, after being so advised by supreme leader Ayatollah Ali Khamenei. The Ayatollah suggested Ahmadinejad throw his support behind his former deputy, Hamid Baghaie.

Ahmadinejad said he remained committed to his "moral promise" to Khamenei of not running for the May 19 election. At the registration center, the former leader stated that the Khamenei's "advice was not a ban. I repeat that I am committed to my moral promise [of not running] and my presence and registration is only to support Mr. Baghaie."

Ahmadinejad left office in August 2013 after two troublesome four-year terms, which left Iran divided, isolated and struggling to find its footing economically.

His 2009 re-election was followed by one the largest protests to hit the country since the Islamic revolution three decades before. Two candidates backed by reformists Mir Hossein Mousavi and Mehdi Karroubi - who have been under house arrest since February 2011 - contested the results. Both Ahmadinejad's terms also sparked anti-Western and anti-Israeli rhetoric, including skepticism towards the Holocaust.

But, Ahmadinejad approach and humble roots make him a popular figure among the poorer sections of society.