Republican Party leader lashes out at Trump's 'rigged' claim

WASHINGTON (AP) -- The head of the Republican National Committee is lashing out at Donald Trump's charges that the party's presidential nomination process is "rigged."

RNC Chairman Reince Priebus responded to the GOP front-runner's intensifying rhetoric on Twitter late Tuesday.

Priebus says the nomination process has been known for more than a year. He says, "It's the responsibility of the campaigns to understand it. Complaints now? Give us all a break."

Trump is going on the attack as he struggles to keep pace with rival Ted Cruz's delegate operation. Cruz made gains in Colorado, North Dakota, Louisiana and elsewhere by mastering the complicated state-by-state delegate selection process.

Trump told supporters in New York on Tuesday night that the "Republican system is absolutely rigged."