(CNN) -- Election night could be a long one. Many of the polls continue to show a tight race with the candidates remaining in a dead heat in the swing states. Whoever wins the election, it might not be by much. Close elections have produced challenges for the victor once he starts his term in the White House. If voters don't provide a clear mandate, presidents often find that they have added challenges when dealing with Congress, as legislators have far less fear about the commander in chief. In 1916, for example, President Woodrow Wilson won reelection against former Supreme Court Justice Charles Evan Hughes by 23 electoral votes and 3.1 percent of the popular vote. The victory, which depended on Wilson's assurances to keep the U.S. out of war, hardened the lines of partisan battle. Republicans returned to Washington angry about how he had used the potential for war against them, even as he ushered the nation into World War I soon after the election.
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Close elections often produce challenges for presidents, says Julian Zelizer
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JFK found most of his legislation stifled in congressional committees, Zelizer says
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Jimmy Carter struggled to win support from his own party on many issues, he says
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Zelizer: After 2004, George W. Bush saw most of his domestic legislative proposals languish
@placeholder was not deterred and governed as if he had a mandate, pushing through a massive tax cut in 2001.