The New Jersey governor and the Texas senator (an old friend of mine) are leading opposite ends of the party, and are likely to be rivals in the 2016 presidential primaries. That’s why I expect that at some point between now and the Republican convention, they’ll form a tacit alliance. They’ll both have an interest in knee-capping some other candidate who is positioned between them.
There’s plenty of recent precedent for this. The campaigns of Bob Dole and Pat Buchanan collaborated in 1996 to knock Phil Gramm out of the race. In 2008, John McCain and Mike Huckabee did what they could to squeeze Mitt Romney from both ends. And in 2011, it was Romney’s turn to work with Michele Bachmann against Tim Pawlenty–which contributed to his not making it to 2012. (The new book Double Down reportedly has info on this.)
In 2015 and 2016, some credible candidate will try to run to the right of Christie but to the left of Cruz: maybe Scott Walker, maybe Marco Rubio, maybe someone else. It seems highly likely that whoever it is will bring Christie and Cruz–or at least their campaigns, and at least temporarily–together.