Looks like there may be a way to get Ben Nelson on board.
Nelson on the Public Option
It appears Ben Nelson is open to getting the public option with an opt out and claims it is more popular than a public option which is very true. The Washington Post polled the Public option as a standalone which got 57% but as allowing States to opt in or Opt out, the poll gauged support at 76%, and that's what Nelson supports.
A public option with opt out for the states wouldn't be perfect but it may be the only way to pass something through the Senate. If that's what it takes then people NEED to be open to it.
"Well, there are different kinds of public options.... What was interesting in the poll numbers that I saw, that while there's support for public option generally, generically, when you start talking about it specifically as it relates to states being able to opt out or opt in, have their own, the support overwhelmingly goes up to 76 percent."