Brian Snyder/Reuters Presumptive GOP presidential nominee Donald Trump says anti-Trump GOP delegates' efforts to dump him at the Republican National Convention would be "totally illegal."

Donald Trump argues that taking the nomination away from him now would be wrong. That he won the most Republican primary votes ever. That he beat 16 contenders. But Trump's favorite argument against the campaign to stop him appears to be that it’s “totally illegal.”

Sadly for Trump, he’s almost certainly wrong.

Because while making that assertion is certainly to his advantage as the “Dump Trump” movement gains traction, a pair of decades-old U.S. Supreme Court cases make clear that a national political party is a private organization with wide latitude as to how it conducts its business.

“The delegates can do whatever they want,” laughed a Republican National Committee member who is deeply familiar with the convention rules, but spoke on condition of anonymity to be candid about the party’s internal matters. “This isn’t going to be a legal issue. This is going to be a political issue.”

Trump’s campaign did not respond to questions from The Huffington Post, but the candidate himself has made his view on the matter plain. On June 17, Trump said in a statement: “Any such move would not only be totally illegal but also a rebuke of the millions of people who feel so strongly about what I am saying.” On June 19, he told NBC News: “They can’t do it legally.”

But the celebrity businessman appears to be relying on state party rules and, in some cases, state laws that require delegates to support the candidate who won their state or congressional district during the primary season. Trump surrogate Scottie Nell Hughes, for example, sent out a tweet last week pointing to a Tennessee statute.

Ever wonder why @realDonaldTrump says delegate unbinding is illegal? BC many states have laws like this one in TN! pic.twitter.com/E4ES4Iy933 — Scottie Nell Hughes (@scottienhughes) June 27, 2016

But the RNC member said the Supreme Court cases -- one from 1975, the other from 1981 -- dealt precisely with that issue. Delegates may face political retribution from local or state party officials, but given the case law, lawsuits or prosecution are highly unlikely to succeed, he said.

And while RNC rules do require convention delegates to vote according to the results of primaries and caucus results in their states, the preamble to the party’s rules states that they are only valid “until the next national convention.”

In other words, the rules governing the Cleveland convention haven’t yet been adopted, and they won’t be until the Convention Rules Committee drafts them and the full convention approves them.

If the anti-Trump “Free the Delegates” group can muster a majority of the 2,472 delegates, they can clearly get rid of Trump through a rules change, the RNC member said.

That nearly all states today even have “bound” delegates is the result of the 2012 primary season. In many of those contests, supporters of former Rep. Ron Paul (R-Texas) swarmed local and state party conventions to win delegate slots to the Tampa convention -- effectively undoing the results of some earlier primaries and caucuses that GOP nominee Mitt Romney won.

The RNC responded with new rules, requiring states holding elections open to voters to tie those results to actual bound delegates. Some states responded by avoiding primaries and caucuses altogether, allocating all their delegates through conventions open to party activists, but not necessarily to voters. Colorado was one such state, and is home to the two delegates leading the “Free the Delegates” movement.

“Anytime he doesn’t win, that's his response: This is illegal, you've stolen it,” said one of the two, Regina Thomson. “The fact that he calls it illegal just makes me laugh."

Yet as she speaks to other delegates, Thomson said, it's clear that Trump’s statements and litigious history are causing some to worry that crossing him will lead to long, expensive court battles they cannot afford.

This isn’t going to be a legal issue. This is going to be a political issue. Republican National Committee member

Anti-Trumpers hope to allay that fear of legal consequences. Steve Lonegan, with the formerly pro-Ted Cruz, now anti-Trump Courageous Conservatives PAC, told delegates on recent conference calls that the group is raising money to pay legal costs for those sued or prosecuted for not voting for Trump.

Similarly, anti-Trumpers point to a new federal class-action lawsuit challenging a Virginia state law that, under the threat of criminal penalties, requires both parties to give all their delegates to the winners of their respective primaries. Not even the state parties paid any attention to it: Both Republicans and Democrats allocated their Virginia delegates in proportion to the votes each candidate received.

The judge in the case has scheduled a hearing for next week. If the judge finds the Virginia law unconstitutional, anti-Trumpers hope, it will show delegates all over the country that not even state laws, let alone state party rules, can overrule the will of a national party.

“With this fresh precedent, delegates will note and understand that Mr. Trump’s protests of illegality are without merit,” said Beau Correll, the Virginia delegate who filed the class-action suit.

Yet even if anti-Trumpers persuade delegates that they won’t risk jail time or a lawsuit for changing the rules, they still face the challenge of lining up 57 votes in the Convention Rules Committee and 1,237 among the full delegation.

The RNC member said it's possible they could do so -- if Trump’s campaign continues to falter. “I think you’ve got to have a combination of bad poll numbers and bad conduct. Meaning something that shakes up the fundamentals at the convention,” he said.

But short of that, he added, the rules that “bind” delegates are probably safe. “The question is: Are there enough votes to do that? I don’t think so. It so goes against the fundamental idea of fairness to change the rules after the fact.”

And Sharon Day, co-chair of the RNC, said Trump has nothing to fear. “Donald Trump is our presumptive nominee, and we'll go to the convention and make him our candidate,” she said. “People have voted in primaries and caucuses across the country, and he overwhelmingly won."

Editor's note: Donald Trump regularly incites political violence and is a serial liar, rampant xenophobe, racist, misogynist and birther who has repeatedly pledged to ban all Muslims -- 1.6 billion members of an entire religion -- from entering the U.S.