Ex-Iranian President Mahmoud Ahmadinejad submitted his name for registration as a candidate in Iran's presidential election in may. This move is considered as a challenge to the authority of Iran's supreme leader Ayatollah Ali Khamenei, who had ordered him not to run. Registration for the may 19 election started on monday and will last five days. Nominees will be screened for their political and islamic qualifications by a vetting body, the guardian council. President Hassan Rouhani is expected to seek re-election but faces a stiff challenge from conservatives who oppose the deal. Allies of rouhani are also concerned about the attractiveness of populist candidates Ex-Iranian President Mahmoud Ahmadinejad named one of his main allies and former deputy Hamid Baghaei as a candidate. Conservatives are worried that Ahmadinejad or Baghaei's presence might split their votes. Ahmadinejad previously served two four-year terms from 2005 to 2013. Under Iranian law, he became eligible to run again after four years out of office. Ahmadinejad remains a polarizing figure, even among fellow hard-liners.