Winning 56.5% of the vote in 2010.
In the Event of a Terrorist Attack Affecting the Election, Who Decides Whether to Delay?What the Constitution and Federal Statutes Say. (FindLaw, 7/21/2004)
As Michael C. Dorf points out, it's not the Presdent's call.
But tinkering with the laws of each state -- or with federal law governing state procedures - may not prove sufficient. The decision whether to postpone a federal election in one state affects the nation as a whole.