I'm not saying it'll be a walk in the park but if he can manage to take Iowa and NH (the first two) then he'll be riding momentum into SC.
Iowa: Walker is leading by a huge margin (25% vs 13% to Paul). There is not much time, and Rand may not win this state.
NH: As per the latest polls, Walker is again leading this state with Cruz in the 2nd position (24% vs 14%).
SC: The main fight seems to be between Walker and Bush.
Looking at the opinion polls, I am pessimistic about his chances.