Trump or any conservative has to get majorities in the early states, not pluralities. DNC RNC rules for the Republican Convention specify that to be entered into nomination for a vote at the convention the candidate has to have won majorities in 8 states else he will not be considered. That guarantees Bush a place since most of the states that will surely vote Democrat in the election will give majorities to Bush especially after Kasich and the rest of the herd of stalking horses drop out and "throw their support" to Bush.
Trump was poll against head-to-head match ups in New Hampshire. Trump beats them all and beats Yeb! by 23%! :
"But even that theory appears to be crumbling, at least in New Hampshire.
According to the PPP poll, Trump would trounce his rivals in head-to-head matchups. The survey found that Trump beat out Carson by 8 points, Walker by 18%, Sen. Marco Rubio (R-Florida) by 19%, and Bush by 23%."