Answer
In the 2009 Iranian presidential election, former President Mohammad Khatami withdrew his candidacy in support of Mir-Hossein Mousavi, a reformist politician. Khatami's endorsement aimed to consolidate the reformist vote behind a single candidate and increase Mousavi's chances of victory against the incumbent president, Mahmoud Ahmadinejad. Despite Khatami's support, Mousavi ultimately lost the election amid allegations of widespread electoral irregularities.