If a single sentence could capture the madness about to hit Cleveland, it's this: You can't bring a water gun to demonstrate outside the Republican National Convention, but you can bring an AK-47.

Despite Cleveland's temporary bans on items as innocuous as tennis balls and bicycle locks downtown, Ohio law will allow demonstrators with radically different viewpoints to openly carry handguns and rifles as they encounter one another outside the convention. And it'll be up to a multi-agency police force of thousands of officers, and demonstrators themselves, to keep things from getting violent.

"This thing is like a woman in labor — that baby is coming no matter what, whether we think we're ready or not," said Steve Loomis, president of the Cleveland Police Patrolmen's Association. "We're going to have two very, very passionate groups of people here, and I'm not judging one side or the other ... . (But) I'm going to have what amounts to a handful of police officers standing between them."

The GOP's national conventions are often heavily protested, sometimes leading to hundreds of arrests. The concern is that Trump's presidential run this year has brought especially passionate opposition from left-wing groups and noticeably vocal support from far-right groups.

A group of white nationalists and skinheads who recently brawled with anti-fascist protesters in Sacramento, Calif., have said they'll attend so they can protect Trump supporters. The New Black Panther Party is also planning to come to Cleveland, though the group's chairman has walked back a statement that his members would be armed.

That's on top of the array of left-wing anarchists, right-wing Oath Keepers, anti-poverty activists, anti-abortion activists and Trump supporters who have signaled their intentions to join the eddy of political views expected to swirl together in the streets, sidewalks and parks outside Quicken Loans Arena. The inflammatory Westboro Baptist Church has also obtained a demonstration permit to join in stirring the pot.

In preparation, officials have been readying for anything, from a mass shooter to chemical or radiological attacks. Police have stocked up on riot gear, and airspace over the city will be restricted starting Sunday. FBI special agents have been knocking on the doors of activists around the country in search of information, or at least to let them know they're watching. Journalists are bringing body armor.

Police departments from as far away as Fort Worth, Texas, are sending up to 2,500 officers to help beef up outdoor security provided primarily by the Cleveland Police Department — which has come under federal scrutiny for its repeated use of "unreasonable and unnecessary force," in the words of a 2014 Justice Department investigation.

Cleveland's municipal court system is prepared to keep staff on hand from 5 a.m. to 1 a.m. during the convention, with a dozen judges available to process up to a 1,000 arrests a day if necessary.

"Hopefully that will be enough," court spokesman Ed Ferenc said, adding that jail officials were trying to free up space in case of mass arrests. Officials plan to live-stream protesters' arraignments.

Hospitals have also prepared. The MetroHealth system, which has the city's longest-serving Level 1 trauma center, sped up construction on a new critical-care facility when it learned the convention was coming to town, said spokeswoman Tina Shaerban-Arundel.

"We definitely saw the value of having those extra ICU beds available just in case something happened," Shaerban-Arundel said.

If Cleveland Police Chief Calvin Williams is nervous, he isn't showing it.

"We've done events in the past where people have presented themselves in an open-carry format and we've handled that," Williams said at a news briefing Wednesday. "Assault rifles, handguns, you name it ... . Our officers are used to it; we've handled it before."

Open-carry laws have drawn extra scrutiny since last week's ambush in Dallas, where a gunman angered by recent police shootings killed five officers and wounded others. Dallas police said they were confused by several protesters who were open-carrying, and at one point wrongly identified a protester with an AR-15 as a suspected gunman.

In response, Williams said, Cleveland police "have sort of tweaked our policy a bit — our tactics — to ensure everybody is safe, including that person open-carrying." He declined to elaborate.

Loomis, the head of the patrolman's association, was more skeptical, and urged demonstrators not to bring guns.

"While it's your legal right to guns in an open-carry type of situation, you have a moral obligation to not make things more difficult," Loomis said in an interview. "I'm here to tell you that this is very irresponsible ideology — to think that you're going to bring guns in here and it's going to make things better. It's not. We saw that in Dallas."

Police officers, Loomis added, were looking forward to getting the convention over with. "You're going to have a lot of people going on vacation the week afterward, I'll tell you that."