Newt had a lot of baggage, decades worth of baggage. He makes Hillary look squeaky clean. Santorum at least had his populism to somewhat compensate for his weaknesses. Newt has lots of baggage, he's gaffe-prone, he's just as right-wing if not more so than Romney and he'd likely melt down on the national stage as he often does ('95 shutdown, before Iowa, before Florida). Newt had many of Romney's weaknesses, few strengths, and more weaknesses and a fragile temperament. Newt is a very weak candidate.