During a White House press conference this morning, Jay Carney was asked whether President Obama has the power to delay Election Day because of the impact of hurricane Sandy.
Carney's answer: "I don't know."
A Constitutional answer: "Hell no."
The Constitution gives Congress sole power regarding the date of the presidential election, and that date is binding on the entire country.
Article 2 Section 1 Paragraph 4 of the Constitution: "The Congress may determine the Time of choosing the Electors, and the Day on which they give their Votes; which day shall be the same throughout the United States."
This empowered Congress to pass a law setting Election Day as the first Tuesday in November during a federal election year, which they did in 1845. And since that time Election Day has been on the first Tuesday in November every year for federal elections, come rain, sleet, or snow.
The only way the power over elections could be extended to the president is through a constitutional amendment process. An attempt to do it by any other means would reveal despotic intent or raw desperation (or both).