Nelson has never been overly popular, not to mention he is one of the most arrogant S.O.Bs in Congress. He keeps winning because the GOP has nominated three losers to face him.
Nonsense. There are very few Republicans who could beat him in a neutral environment. I'd bet that the only Republican who could have won last year would have been Jeb Bush himself, and that would have been a real race. The Florida GOP don't nominate duds very often (Katherine Harris aside). He keeps winning by filling the perfect niche of being liberal enough to win primaries but not too liberal to lose the goodwill he's built up with business owners, moderate republicans and former southern Democrats that carries him over the finish line.
I'd support him over Scott in an instant, and I'd bet every dollar I have that he'd beat Crist in the primary. Florida Democrats wouldn't be supporting him if they had a legitimate candidate who could win; Nelson could most definitely win. I've always thought Scott's chances were better than polls showed because Crist's support is so ephemeral; most of his supporters (with notable exceptions) doesn't really LIKE him, they either tolerate him because they want to win or out of expectation of future rewards if he wins. His lead has already shrunk and will (I believe) continue to shrink as Scott really gets on the airwaves and reminds people of who they're voting for. I don't think Nelson has done anything that would stick as much, even with a vote for Obamacare. I hope he decides to jump in.