"You cannot be a conservative if you're going to keep promoting new programs you're not going to pay for," said Paul.

Marco's retort triggered the loudest cheers of the night:

"There are radical jihadists in the Middle East beheading people and crucifying Christians. The Chinese are taking over the South China Sea. … the world is a safer and better place when America is the strongest military power in the world."

Having called for the U.S. Navy to confront Beijing in the South China Sea, and for establishing a no-fly zone over Syria that Russian pilots would enter at their peril, Rubio seems prepared for a confrontation with either or both of our great rival nuclear powers.

Dismissing Vladimir Putin as a "gangster," Marco emerged as the toast of the neocons. Yet the leading GOP candidate seems closer to Rand.

Donald Trump would talk to Putin, welcomes Russian planes bombing ISIS in Syria, thinks our European allies should lead on Ukraine, and wants South Korea to do more to defend itself.