With the U.S. presidential election in a dead heat, President Barack Obama and his family may be concerned that their time in the White House could be running out. While the idea of Mitt Romney living in their home might be creepy enough, the Obamas could have trouble sleeping because of some of the ghosts said to walk the halls of the residence at 1600 Pennsylvania Ave. in Washington.

The ghost -- or the presence -- reportedly seen most often lurking around the White House is that of Abraham Lincoln, which is not a surprise to psychics who have said that the 16th president’s assassination doomed him to a second life as a spirit. Curiously, the most sensational sightings of Lincoln’s ghost all came at times when America was approaching great challenges, according to the History Channel.

Grace Coolidge, who was the first lady to President Calvin Coolidge just before the Great Depression struck, reported seeing Lincoln ominously looking out the window of the Oval Office, in the direction of what was once a Civil War battlefield. President Lyndon Johnson’s wife, Lady Bird Johnson, also mentioned feeling Lincoln’s aura when she was watching a TV show about him.

Perhaps unsurprisingly, then, Lincoln’s ghost was seen around the White House during World War II. It walked in on British Prime Minister Winston Churchill smoking a cigar naked, and it is said to have joined first lady Eleanor Roosevelt on more than one occasion when she used the Lincoln Bedroom as her study late at night.

A young staffer during President Franklin Delano Roosevelt's administration supposedly saw Lincoln's shade enter a room, calmly sit down, and remove its boots, according to About.com, which also reported that Queen Wilhelmina of the Netherlands said she heard knocking on her door, which led her to open it and find Lincoln’s specter in her doorway wearing his trademark top hat.

Even in Lincoln’s time, though, there were reports of presidents who came before him not being quite ready to leave. Mary Todd Lincoln, his wife, said she saw the ghost of President Andrew Jackson cursing in the Rose Guest Room, which sits inside the first family’s living area. According to Suite101, other White House guests have reported hearing and seeing Jackson laughing -- loudly -- in the Red Room.

The spooky quality that’s contributed to Washington D.C. Ghost Tours wasn’t lost on President Harry S. Truman, who wrote a letter to his wife about sensing Jackson after he took office.

“I sit here in this old house and work on foreign affairs, read reports, and work on speeches -- all the while listening to the ghosts walk up and down the hallway and even right here in the study,” Truman wrote. “The floors pop and the drapes move back and forth -- I can just imagine old Andy [Jackson] and Teddy [Roosevelt] having an argument over Franklin [Roosevelt].”

Not all of the White House's paranormal activity is attributed to presidents, however: First lady Abigail Adams is said to still hang laundry in the East Room, where the smell of clean linen is often reported. And there have also been rumors of a British soldier who walks the halls of the building carrying a torch, perhaps a leftover from the War of 1812.