“I know the rules very well, but I know it’s stacked against me by the establishment,” the GOP frontrunner said.

But RNC chairman Reince Priebus battled back against Trump’s criticism.

“Nomination process known for a year + beyond. It’s the responsibility of the campaigns to understand it. Complaints now? Give us all a break,” he tweeted.

Earlier, Trump alleged the GOP’s selection process was “absolutely rigged … a phony deal” after Cruz swept Colorado’s 34 delegates over the weekend.