Posted some info on the chances Newt has to pick up delegates after Super Tuesday in
my big thread.
Basically, there's a huge gap where Newt has essentially zero chance of picking up any delegates (outside of Puerto Rico) between March 13 (AL/MS primaries) and May 8 (NC primary), unless he drastically improves on a national level.
At the very least, if he fails to win any delegates in Alabama (there's a 20% threshold), he should drop out.
After a certain point, he's probably
decreasing the chance of a brokered convention by staying in, by running the risk of acting as a spoiler and handing certain WTA states to Romney.