Syria’s main opposition leader has announced his resignation in the latest sign of deep divisions among those fighting President Bashar al-Assad. Moaz al-Khatib said he was quitting as president of the Syrian National Coalition, “so that I can work with freedom that is not available inside the official institutions.” Al-Khatib had faced criticism from his own ranks for offering to negotiate with Assad. In a further sign of turmoil among anti-government groups, the coalition’s military chief has rejected the authority of Ghassan Hitto, a U.S. citizen recently elected as interim prime minister over rebel-held areas. General Salim Idris said Hitto, a former technology manager who lived in Texas, lacks a broad base of support in Syria.