No one can know for certain which events had what effect on the election. It’s certainly true that it was so close that anything was potentially decisive. It seems pretty clear that the Comey letter had a bigger effect than WikiLeaks, though. The drip-drip of WikiLeaks kept a negative narrative about Hillary out there, but most of the material was of gossipy interest and covered much more in the conservative press than the mainstream media. A particular exception was the Doug Band memo, which put in black and white how the Clinton Foundation was a profit center for Bill and his cronies. But none of this really compares with the Comey letter, which led to an immediate and discernible drop in Hillary’s poll numbers. When Hillary said that both the Comey letter and his last-minute exoneration hurt her, it may have sounded whiny, but it’s very plausible. This is why the Left tends to lump in Comey with the Russian hack (see the Paul Krugman column below), even though Comey is obviously an American official who not too long ago every Democrat in the country was praising for his patriotism and discernment. Comey may have made the wrong call in his handling of the discovery of the Abedin emails, but all campaigns tend to have unpredictable events and a stronger candidate without Hillary’s ethical lapses wouldn’t have been so vulnerable to begin with.