Indeed, while Donald Trump and Ted Cruz duel for first, the battle between these Floridians has become a primary of its own, with the loser likely to face significant pressure from donors to plot an exit from the race, according to sources close to both men.

“It’s a cage match. One man wins, one man leaves. This is a political reality,” said South Carolina Rep. Mark Sanford, a former two-term Republican governor. “Any comparisons and contrasts will be made.”…

Not everyone sees South Carolina as do or die for Bush and Rubio, however. With Nevada holding its primary three days later, on Feb. 23, and a large slate of southern states voting on March 1, some see the two fighting it out for weeks to come – regardless of who beats out whom in South Carolina. They may even go head-to-head in a home state dual in Florida, which holds its primary on March 15.

“Florida will be the real climax and the state that truly determines which of them continues in the race,” said Christian Ferry, who served as campaign manager for Lindsey Graham’s presidential bid. “South Carolina is another battle in the war, but I think it is far from anyone’s Waterloo.”