SEC Primary Day March 1, 2016
Clinton should have a easy and sizable win over Sanders in South Carolina.
Of the March 1 primary contests for the Democrats, Sanders will win in Vermont as that is his home state. He may finish close or even win in Massachusetts. But everywhere else, he is looking at 10 to 20 percentage point defeats.
On the GOP side, here is a list of the states involved. Polling data exists for some states while it is sparse in others.
Alabama - no recent data
Alaska - caucus, limited data and hard to poll anyway
Arkansas - limited data show 3-way race
Georgia - recent data has Trump ahead
Massachusetts - recent data has Trump ahead
Minnesota - caucus, limited data and hard to pool anyway
Oklahoma - limited data show 3-way race
Tennessee - no recent data
Texas - recent data show Cruz ahead
Vermont - limited data but Trump ahead
Virginia - recent data has Trump ahead
Cruz definitely needs to win Texas and would want to win at least 1 or 2 other states. Rubio needs a win somewhere, anywhere. As for Trump, if he carries 11 for 11, it is over. One might even say 10 of 11 (losing Texas), it is over.
Update: I hear there are some complicated rules about Texas. If Cruz wins with 50%+1 then he would get all the delegates in Texas. Otherwise, it is proportional. Cruz needs a win of any size but prefers a bigger win.
Update: Another factor I have heard is "threshold." If one is below some cut-off (15 or 20%) then that candidate gets no delegates. Thus, winning a state is preferable but the key is to collect delegates and minimize the number that Trump gathers. Although Cruz wants to win Texas and somewhere else as does Rubio wants to win anywhere, the real key is to collect delegates. For Cruz or Rubio to get shut out of delegates from any state would be a problem for them. They will hope to capture enough delegates so that Trump racks up 50% or fewer of the delegates from Super Tuesday.