Reince Priebus speaks at the 2016 Conservative Political Action Conference (CPAC) on March 4, 2016. REUTERS/Joshua Roberts The head of the Republican National Committee on Sunday discounted the "rhetoric" of his party's presidential frontrunner, Donald Trump, about what Trump has called a "rigged" system that's used to pick the party's presidential nominee.

Trump has blasted party's delegate rules over the past week. Among other things, last Thursday, he wrote an op-ed for The Wall Street Journal complaining that he could lose the Republican nomination despite having won more votes in state contests.

He also warned at a Saturday rally in Syracuse, New York, of a "rough July" if Republicans head into a contested convention in Cleveland.

"The Republican National Committee, they'd better get going," he said. "Because I'll tell you what — you're going to have a rough July at that convention."

RNC Chair Reince Priebus dismissed Trump's criticisms on Sunday.

"Since I know what the truth is, I don't really worry about it because I know what is right and I know what is wrong," Priebus told CNN.

He continued:

If you think [Trump's assertion the system is rigged is] rhetoric, if you think it's hyperbole, you know, look — there's nothing that the RNC can do to alter the rules between now and the convention. It's not the RNC's place. So I don't sit here and internalize the charge, because there's no there there. There's nothing the RNC can do about it. Everyone knows what the rules are. Everyone knows that the RNC can't change the rules between now and the convention.

With three Republicans — Trump, Texas Sen. Ted Cruz, and Ohio Gov. John Kasich — still in the race for the party's nomination, a contested convention is looking increasingly likely.

To win the Republican nomination outright, a candidate needs 1,237 delegates. If no one in the party wins that many through state contests, many delegates that would be bound to Trump on the first ballot of convention voting could vote for whomever they want on subsequent ballots.

Trump criticized this system in his Wall Street Journal op-ed, after raging much of last week against Colorado's election system. Earlier this month, Cruz swept up delegates in the state's Republican convention, which the state held in favor of a system featuring a popular vote. Last weekend, Cruz also dominated in Wyoming, which has a similar system.

"My campaign strategy is to win with the voters," Trump wrote. "Ted Cruz’s campaign strategy is to win despite them."

He continued: "What we are seeing now is not a proper use of the rules, but a flagrant abuse of the rules. Delegates are supposed to reflect the decisions of voters, but the system is being rigged by party operatives with 'double-agent' delegates who reject the decision of voters."