Cruz and his allies have sought to make this a two-man race, with Cruz battling Trump. When Trump decided to sit out the Fox News event, Cruz challenged the billionaire businessman to a one-on-one debate that would have served to keep him closer to the front-runner.

But Cruz can’t seem to leave the pack behind. A loss in Iowa, or even a close finish by Trump and Rubio, would deal a big blow to his theory of the race, and put him on shakier ground going into later states…

After spending weeks in the fall trying to paint Rubio as a moderate, Cruz had largely moved on, training his fire on Trump instead for the short-term. Instead, the money is going back to fighting Rubio over his support for “amnesty.”

“He’s not worried about Rubio beating him in Iowa,” said Erick Erickson, a conservative personality in close touch with the Cruz team. “But they’re looking now to the future: Does Rubio come out of Iowa strong enough to get through South Carolina and actually keep himself going? And I think that’s got to be a real concern from the Cruz campaign.”