Mahmoud Ahmadinejad is an Iranian politician who served as the sixth president of Iran from 2005 to 2013. Ideologically a principlist and nationalist, he was a member of the Expediency Discernment Council and a strong proponent of Iran's nuclear program. He was also the main political leader of the Alliance of Builders of Islamic Iran, a coalition of conservative political groups in the country, and served as the mayor of Tehran from 2003 to 2005, reversing many of his predecessor's reforms.