(Reuters) - When Chris Cox rolls into Cleveland in mid-July with other motorcycle-riding supporters of Donald Trump, he plans to celebrate the billionaire’s coronation as the Republican presidential nominee. He also counts on joining protests if a battle over the nomination ensues.

Organizer Chris Cox speaks at a Bikers for Trump 2016 rally at Jergel's Rhythm Grille in Warrendale, Pennsylvania April 24, 2016. REUTERS/Alan Freed/File Photo

“I’m anticipating we’ll be doing a victory dance,” said Cox, 47, a chainsaw artist and founder of Bikers for Trump, thousands of whom he estimates will hit the Ohio city for the July 18-21 Republican National Convention.

“But if the Republican Party tries to pull off any backroom deals and ignores the will of the people, our role will change.”

Bikers For Trump is part of a diverse array of groups coordinating to hold thousands-strong protests and marches if the real-estate mogul is denied outright victory at the Republican Party’s nominating convention in Cleveland.

The risks of confrontation and violence surrounding Trump events were highlighted again on Thursday, when around 20 people were arrested following clashes between anti-Trump protesters and police outside a rally for the candidate in California. It was the worst outbreak of violence since Trump was forced to cancel a rally in Chicago in mid-March.

Anti-Trump protests are expected in Cleveland. In late March, the left-leaning National Lawyers Guild held a conference in the city to coordinate legal support to protesters in the event of mass arrests during demonstrations.

Leaders and members of the pro-Trump groups told Reuters their main goal is to mount a show of support for their candidate, who after a series of primary victories this week looks increasingly likely to clinch the nomination outright ahead of Texas Senator Ted Cruz and Ohio Governor John Kasich.

But if he falls short of the required 1,237 delegates, raising the risk he could lose out in a contested convention, they said they plan to do all they can to exert pressure on party leaders to prevent someone else getting the nomination.

Several Trump supporters suggested that tensions could escalate if the party was seen as trying to deny Trump the nomination despite his commanding lead in delegates won in primary contests.

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“The plan either way is send a message to the Republican establishment to respect our votes,” said Ralph King, a member of the Cleveland Tea Party. “If the party tries to parachute in a white knight to steal the nomination, it’s not going to end well.”

Trump has said that if he fails to get the nomination there will be “riots.” Though there have been violent incidents at some Trump rallies, organizers insist they work closely with the authorities to avoid violence.

The U.S. Secret Service is the lead agency for the convention. Its spokeswoman Nicole Mainor said protests or violence for such an event are “factored into all of our contingency plans that have been built up over many, many months.”

The Cleveland Division of Police also has a security plan in place as it does for all major events of this kind, a spokeswoman said in an email, without providing further details.

Bikers for Trump, which Cox founded in August and which he claims has 30,000 members and rising, is just one of a mixed bag of pro-Trump groups that aim to be in Cleveland. Reuters could not independently verify Cox’s membership claims for the group, which has provided unofficial security at Trump rallies around the country.

Pro-Trump groups planning a presence in Cleveland include some Tea Party-affiliated organizations, a new group called Stop The Steal led by Trump ally Roger Stone, Citizens for Trump, and the Truckers for Trump group.

King, a veteran of Tea Party rallies, is coordinating with other groups and local police to obtain permits for marches and protests during the convention, and to hold a major rally in downtown Cleveland that will then march on the convention site.

“STOP THE STEAL”

Stone plans to raise $262,000 through online donations to hire buses and is negotiations with colleges in the Cleveland area on sleeping space for activists. He says he wants Republican delegates Trump has won in primaries to sign a “voluntary pledge” to back him beyond the first ballot should there be a contested convention. He did not disclose how much money the group has raised.

Citizens for Trump co-founder Tim Selaty says he will have activists filming events inside the convention center and broadcasting them live on social media “to document every move.”

“If Mr. Trump walks into the convention center a couple of hundred votes ahead of Cruz and loses the nomination, it will not be a pretty scene,” Selaty said.

Truckers for Trump says it has 4,000 members and that more than 1,000 are committed to driving their big rigs to Cleveland.

The pro-Trump groups say they are not seeking confrontation but fear that opponents of their candidate might start trouble.

“Our members will instructed that if there’s trouble to stand back and let law enforcement do its job,” said Matthew Heimbach, founder of the Traditionalist Workers Party, a “pro-white nationalist, pro-working class” party, which plans to have a few dozen members in Cleveland.

It is unclear is how many nationalists or white supremacists might attend. Trump has adherents on the far right, including former Klu Klux Klan grand wizard David Duke, who told his radio show listeners in February that voting for anyone other than Trump was “treason to your heritage.”

The National Socialist Movement, a prominent white nationalist group, told Reuters it did not plan any events.

Brian Culpepper, a spokesman for the Detroit-based group and a Trump supporter, said many members support the mogul. But it does not officially back Republican or Democratic office seekers as it wishes to replace the current system with a white nationalist power structure.

“Our members are free to attend events in Cleveland as individuals,” Culpepper said. “But we do not plan anything as a group.”