It's too bad that Abbas has started picking up on this Israeli lingo about "red lines". Israeli politicians got this from the military, since that is the training ground for the country's politicians. "Red lines" is just not an expression that is used much outside Israel, and certainly not in the US. It is bad negotiations to set out beforehand all the things that you won't accept. Notice that Obama and the State Dept. talk about "principles" on which a solution should be based, not "red lines".
U.S. Catholics largely open to non-traditional families, Pew survey finds (DPA)
from the article: Abbas to U.S.: Peace talks won't work until Israel given red lines