That's all he has left now. He can't win a majority of delegates, not in the Trump friendly states coming up. His only hope is to win over the GOPe at a contested convention.
His other option is to ally with Trump any block the GOPe, but that would involve accepting the VP slot (Trump has to be on top or no deal) and convincing Trump to give it to him.
That seems less likely every day.
We're going to have to listen to deluded Cruz supporters ranting about his "ground game" right up to the moment Trump gets an absolute majority of delegates or when the GOPe stabs Cruz in the back at the convention.
Trump and Cruz are playing chicken, and the fate of the country is determined by whether one of them turns chicken, avoiding the fatal crash. If neither diverts his path, both lose — along with the rest of us. If that happens, it will just show that both of them — like all the other Republicrats — are more interested in themselves than in their country.
Let’s hope that the two of them can figure out the art of the deal. Combining their votes would make it almost impossible for the GOPe to deny them.