It's pretty hard to imagine a road to the White House that doesn't run through Florida.
Most electoral maps put the Democrats at at pretty solid 217 electoral votes, plus a 30 point lean from Wisconsin and Pennsylvania. That makes Florida's 29 electoral votes the key to the election.
Sure, if Walker is the candidate, that takes away Wisconsin's 10, but it also means the names "Bush" or "Rubio" don't lead the ticket, making Florida that much easier to win.