US Ambassador to Japan Rahm Emanuel might return to politics by running to lead the Democratic Party.Lorenzo Bevilaqua/ABC via Getty ImagesRahm Emanuel reignited one of the longest-running debates about Obama's legacy.Emanuel said more Wall Street bankers should have faced justice.Now Biden's US ambassador to Japan, Emanuel is considering a possible run to lead the Democratic Party.Former Obama White House chief of staff Rahm Emanuel said on Tuesday that it was a mistake that more top Wall Street executives didn't pay a price for their role in the 2008 financial crisis."Not only was no one held accountable, but the same bankers who engineered the crisis were aggrieved at the suggestion of diminished bonuses and government intervention," Emanuel wrote in a Washington Post op-ed.