TEHRAN — President Mahmoud Ahmadinejad received praise from Iran’s reformist politicians and withering criticism from its conservatives after he sent Barack Obama a letter last week congratulating him on winning the American presidential race. But in a sign that conservatives fear their attacks might inadvertently strengthen a possible reformist candidate in Iran’s own presidential vote in June, their criticism has quickly shifted to early support for Mr. Ahmadinejad’s re-election. The potential opponent is former President Mohammad Khatami, the moderate Mr. Ahmadinejad bested in the last elections in 2005. Mr. Khatami has not yet announced his candidacy, but is under pressure from his political allies to run. … >>>