Donald Trump campaign manager Corey Lewandowski on Sunday dismissed criticism about his team failing to understand GOP delegate rules and declared his candidate the party’s “presumptive nominee."

Lewandowski told “Fox News Sunday” that the Trump campaign indeed comprehends the rules -- which vary among states and sometimes apply to conventions, not primaries or caucuses.

Nevertheless, he thinks the rules are not always fair.

“We understand what happens,” said Lewandowski, arguing primary challenger Texas Sen. Ted Cruz does better in state contests in which “party bosses pick the delegates,” not the voters.

He added: “There are people out there who don’t have the ability to write a check,” to become a convention-picked delegate.

Trump, Cruz or Ohio Gov. John Kasich will need 1,237 delegates to win the Republican Party nomination.

Trump leads with 744, followed by Cruz with 559 and Kasich with 144.

While Trump also has won roughly 20 state contests with larger delegate pools, Cruz has been able to win a dozen or so delegates by essentially campaigning at the smaller-scale state and county conventions -- like those in Colorado and Wyoming on Saturday in which Cruz won all 14 delegates.

Ken Cuccinelli, Cruz’s delegate operations director, said on ABC’s “This Week” that the Trump campaign must stop accusing Cruz of not following the rules and using “hyperbolic rhetoric” about the issue that it cannot support.  

Republican National Committee Chairman Reince Priebus said last week on Twitter that the nomination process has been known to all for more than a year and that the campaigns have a responsibility to understand the process.

“Complaints now?” he tweeted. “Give us all a break."

Trump, during a campaign event Saturday in Syracuse, N.Y., suggested the Republican establishment and others are going to have a “rough week” at the party’s nominating convention in July if he arrives with a large delegate lead and officials try to take it from him.  

“That’s not what we’re about,” Lewandowski said Sunday, attempting to clarify Trump's remarks. “We’re supposed to be bringing this party together. If the party wants a nominee (who can win the White House), it needs to pick Donald Trump.”

Lewandowski also said Trump, a billionaire businessman, will do “very well” in the New York primary Tuesday in which 95 delegates are at stake, but declined to predict a sweep amid strong polling numbers.

However, he predicted Trump also will do well in upcoming mid-Atlantic state contests, including those in Connecticut, Maryland, Pennsylvania and Rhode Island.

“He’s going to be the presumptive nominee going forward,” Lewandowski said.

Paul Manafort, Trump's newly hired convention manager, told The Washington Post in a story Sunday the campaign’s goal is for Trump to be the presumptive nominee by mid-May.

Lewandowski also on Sunday said that he was happy that Palm Beach County (Fla.) officials decided last week not to proceed with charges that he allegedly assaulted a reporter by grabbing her arm.

He declined to apologize for the incident and for calling her “delusional” for saying he grabbed her. However, Lewandowski said he would speak privately with the reporter in an attempt to put the issue behind them.

Lewandowski has said he tried to call the reporter, Michelle Fields. She says he did not. Lewandowski told “Fox News Sunday” that police have phone records showing he did.