Nelson, 70, flew on a space shuttle mission while in Congress, and is a strong proponent of the space program. He co-sponsored legislation in 2010 that lays a foundation for continued space exploration.
For a senator with a target on his back, he didn't spend much time in public making a case for his re-election.
Mack tried to make a splash in this race whenever he could. He made sure he was with Romney or running mate Paul Ryan when they made one of their frequent visits to the state, knowing his fortunes were tied to the top of the ballot.
He called for more debates after the candidates only got together once. The hour-long affair was held before prime-time and gave the candidates little time to detail how they would address the rising cost of Medicare and Social Security, the budget deficit and health care. It was more of a name-calling, finger-pointing debate than a discussion on federal policy.
Mack spent the last three weeks traveling thousands of miles around the state by bus, though he spoke before mostly small crowds, often times just 20 or 30 people.
Nelson held only a couple of events. He attended a press conference Saturday calling for an extension of early voting, and on Monday, he waved signs in Orlando, where he lives, and in Melbourne, where he grew up. He also made an appearance with first lady Michelle Obama.
At Mack's election party, James Doerning, 65, of Cape Coral said he thought Mack would do well in southwest Florida, but he noted Nelson is from Orlando, a key area in the state to win.
"I like his father a whole lot," Doerning said of Mack. "I think one of the biggest things going for him is his age compared to his opponent."
Farrington reported from Bonita Springs, Fla.