DES MOINES, Iowa -- Donald Trump has waged an assault on the rules that govern how Republicans choose their nominee, which many in the party say is coming far too late to change what they acknowledge is a complicated selection system.

Instead, some party members say, his railing against a "rigged" process appears aimed at amplifying his central message to an angry electorate: America is a mess, and only Trump can clean it up.

Trump says the process should favor the candidate who wins the most votes during the primary campaign. He has received about 8.2 million votes to date, about 2 million more than his closest competitor, Sen. Ted Cruz of Texas.

But Cruz is outmaneuvering Trump in lining up support among the individuals who will attend the Cleveland convention as delegates. That's a separate process, in which party activists seek the positions primarily through local, district and state party conventions.

Underlying the criticism, Trump's goal is to rally supporters and pile up primary season victories that would allot him the 1,237 delegates needed to win the nomination outright before the summer convention. But it's a tactic that Republicans say carries risks for the businessman.

Should Trump fall short of clinching that number going into the Cleveland convention in July, they said, his criticism of the party is likely to annoy the delegates who would then decide the nominee.

"He is trying to pit voters against the very people who make the decision of whether he gets the nomination," said Matt Borges, chairman of the Republican Party in Ohio. "If he does not arrive in Cleveland with 1,237 pledged delegates, then there is no way he gets the nomination."

Reince Priebus, chairman of the Republican National Committee, took to Twitter to make the point that the nomination process has been known to all for more than a year.

"It's the responsibility of the campaigns to understand it," Priebus wrote. "Complaints now? Give us all a break."

Priebus said Sunday on NBC's Meet the Press that he will not allow Trump to bully him, noting that a majority -- not a plurality -- rules in most aspects of governance.

In the Wall Street Journal on Friday, Trump equated the party's nomination procedures with the "unfair trade, immigration and economic policies that have also been rigged against Americans."

He added, "Let me ask America a question: How has the 'system' been working out for you and your family?"

If Trump can't clinch enough delegates by the last primaries, on June 7, then those delegates will largely be free after the first ballot at the convention to vote for the candidate of their choice.

Trump said he has all the tools he needs to assuage delegates, if he chose to do so.

"Nobody has better toys than I do," Trump told attendees Sunday at a GOP brunch in Staten Island, N.Y.

"I can fly [delegates] on the best planes and take them to the best resorts around," including his private club in Florida, Mar-a-Lago. "You're basically buying these people. You're basically saying, 'Delegates, listen, we're going to send you to Mar-a-Lago on a Boeing 757, you're going to use the spa, you're going to this, you're going to that.' That's a corrupt system. That's not a democracy."

On Friday, the Republican party's chief strategist, Sean Spicer, laid out the rules for elected delegates in each of the remaining states that will hold primary contests.

Spicer noted those rules were shared with all the campaigns last year, adding that "each process is easy to understand for those willing to learn it."

Several of those involved in the rule-making process said they believe there's a consensus inside the party against considering changes before the convention.

"We want to avoid even the appearance that somehow the RNC is trying to meddle or manipulate the convention process," said Peter Feaman, a Florida GOP committeeman.

Ron Kaufman, a longtime member of the RNC's standing rules committee, said: "To be fair, it's complicated for everyone. And I understand why someone who's never done it before, and hasn't taken time to learn it, gets frustrated."

But that frustration isn't winning Trump any friends among the party officials who will have sway in the event of a multiballot convention.

Henry Barbour, also a rules committee member, said Trump's attack on the party and the delegate selection process is bad politics.

"If you want to ask a girl to the prom, you don't tell her how ugly she is the week before," Barbour said.

Trump said Sunday that he hoped the Republican convention in July "doesn't involve violence," as he pressed his case that the system is rigged against him.

Trump made the statement at a news conference on Staten Island after he was given an award by the New York Veteran Police Association and spoke at the Republican brunch.

He added, "I don't think it will. But I will say this, it's a rigged system, it's a crooked system."

Trump stopped short of saying he would not accept the nominee if it was someone else, saying he had to see how the process played out.

"I have to see how it's handled and what level of fairness" he is afforded, Trump said.

Democratic race

After weeks of hosting packed rallies around New York state, Sen. Bernie Sanders of Vermont, a Democratic presidential candidate, made his case Sunday at a predominately black church service.

Sanders visited First Corinthian Baptist Church in Harlem to speak with the Rev. Michael Walrond Jr. about his past civil-rights work, the need to overhaul the criminal justice system and his experience growing up in a family fraught with financial stress.

Sanders spoke two days before New York's primary, a contest that he has said is crucial to his campaign and that he is counting on to help him overcome Hillary Clinton's large lead in pledged delegates.

At First Corinthian Baptist Church, Sanders told members that he learned important economic lessons from watching his parents argue over not having enough money. He also said he was moved to protest segregation as a college student because he was interested in social justice.

"We need a candidate now who has the track record, the agenda and the guts to stand up to the billionaire class," Sanders said.

Sanders added that he believes many of the goals of Martin Luther King Jr. remain unrealized and pointed out that black people continue to be underpaid and lack access to affordable housing and proper health care. He also said he learned about racial profiling by talking to people who regularly experienced being "harassed" and "intimidated" by police officers.

"I learned from Black Lives Matter," Sanders said to applause. "What I learned is how police in white communities are regarded very differently than police in black communities."

Clinton and her husband, former President Bill Clinton, have visited several churches during the New York primary season. Some of the churches the Clintons visited include Christian Cultural Center in East New York, Brown Memorial Baptist Church in Clinton Hill, Mt. Pisgah Baptist Church in Bedford-Stuyvesant, Abyssinian Baptist Church in Harlem and Greater Allen AME Cathedral in Jamaica, Queens.

While Sanders was visiting the New York City church, his campaign began a new fundraising pitch using comments from actor George Clooney, who raised hundreds of thousands of dollars for Hillary Clinton over the weekend, that the amount of money in politics is "obscene."

The Sanders campaign sent out an email to supporters asking for donations and quoting comments Clooney made on NBC's Meet The Press. The actor helped lead an event in San Francisco to raise money for the Hillary Victory Fund on Friday night. For seats at the round-table dinner with Clooney; his wife, Amal; and Hillary Clinton, a couple had to pay or raise $353,400, the network reported.

When asked about Sanders' criticism of the event, Clooney said he agreed with the senator.

"Yes. I think it's an obscene amount of money," Clooney said. "The Sanders campaign, when they talk about it, is absolutely right. It's ridiculous that we should have this kind of money in politics. I agree completely."

Meanwhile Sunday, Clinton sought to clarify her shifting position on a $15 federal minimum wage, saying that she would sign legislation enshrining that figure if pay rose gradually and if the law included escape clauses similar to those approved this month in New York state.

"If it has the same kind of understanding about how we have to phase this in, how we have to evaluate it as we go, if the Congress passes that, of course I would sign it," Clinton said in an interview on ABC's This Week.

Sanders has accused Clinton of being vague and inconsistent on raising the minimum wage and has won significant popular support with a promise of an increase for every worker.

During a contentious debate with Sanders last week, Clinton appeared to shift her position from a $12 federal minimum wage, but she insisted Sunday that the Sanders campaign is "trying to make something where there is nothing."

Information for this article was contributed by Thomas Beaumont, Steve Peoples, Jonathan Lemire, Alan Fram and Bill Barrow of The Associated Press; by Yamiche Alcindor and Maggie Haberman of The New York Times; and by Anne Gearan and John Wagner of The Washington Post.

A Section on 04/18/2016