Not every Trump rally merits a red-font headline but this one does, just because the odds of chaos inside and/or outside the arena tonight are unusually high. There are many shadows hanging over this event — Charlottesville, immigration, a possible pardon for Joe Arpaio, a looming clusterfark pitting Trump against his own party’s leadership over Jeff Flake’s reelection bid. Per the NYT, at least one local Antifa pack has called for “an anti-fascist & anti-colonial contingent against Trump’s rally” but they’re only one of several groups who are planning to show:

Several opposition rallies and marches have been planned, according to the Arizona Republic. By Tuesday, more than 3,900 people had indicated on Facebook that they would attend one event, Protest Trump Downtown Phoenix, across the street from the convention center. Another 2,700 said they planned to attend White Supremacy Will Not Be Pardoned, organized by the Puente Human Rights Movement.

Another rally, Never Again: Jews and Allies Against Hate, was planned by David Schapira, a Tempe city councilman, and State Senator Robert Meza for the State Capitol earlier in the afternoon. A church in Phoenix also scheduled a march from the convention center to the Capitol Tuesday evening.

The mayor of Phoenix, Greg Stanton, asked Trump last week not to hold this rally, then asked him again in a WaPo op-ed published this morning. Stanton’s a Democrat so 90 percent of his “concern” is garbage partisan posturing, but not quite 100 percent. Obviously, with feelings running hot after Charlottesville and plenty of Trump supporters in a red state like Arizona willing and able to come out to meet Antifa thugs, there’s potential for another ugly scene on an American city’s streets.

Inside the arena, meanwhile, only Trump knows how tense things might get. This could be a placid, kumbaya-style clean-up of his Charlottesville comments of 10 days ago, building on the theme of national unity he set forth last night in his speech at Fort Myer about Afghanistan. Or it could be a total Trumpian sh*tshow in which he decides to riff about the bad rap given to some of the “very fine people” among the alt-right. Given how much the president enjoys playing to the crowd at his rallies, I’m guessing the subdued option probably isn’t the one he’s going with. Nothing would rev up the crowd quite like a surprise pardon of Sheriff Joe Arpaio, something Trump has openly discussed with reporters lately, but the word as of this afternoon was that it’s not happening:

https://twitter.com/BenjySarlin/status/900095115729010688

Or rather, it’s not happening tonight:

https://twitter.com/EvanMcS/status/900098513278615552

Holding off on a pardon is the prudent move politically, as Democrats are ready to use it to prosecute the case vis-a-vis Charlottesville that Trump is a racist playing to the worst elements of his base. “Some of Mr. Trump’s advisers worry that a pardon could deepen the racial wounds exposed in the last week and compound the president’s political problems,” as the Times delicately put it. I’m sure, if Trump had his druthers, he’d invite Arpaio onstage for a theatrical display of presidential clemency to roars from the crowd, but he’s going to cut his losses after a tough 10 days. Arpaio’s not even invited to tonight’s rally. I suspect the pardon will come eventually, just in a lower-profile setting and more opportune time.

What about Jeff Flake, though? It’d be bizarre for Trump to pass on a chance to flame his archenemy in the Senate in his own backyard, especially with Flake opponent Kelli Ward and her supporters begging for some presidential recognition. Trump gave her a boost on Twitter a few days ago but an endorsement at a nationally televised event would mean much more. It would drive Mitch McConnell and Senate Republicans crazy too, which is reason enough to think he might do it:

As Trump prepares for a rally in Phoenix on Tuesday, some expect him to expand on his support for Ward and searing criticism of Flake — and perhaps even make a formal endorsement.

That possibility has unnerved Republicans inside and outside the White House. Some worry about straining the president’s already tenuous relations with congressional Republicans at a time when they face several key challenges this fall: raising the debt ceiling, passing a spending bill and tackling their top policy objective of new tax legislation. Others looking ahead to next year’s midterm elections think Trump may even be putting the Senate GOP majority at risk.

Allies of Flake, including Senate Majority Leader Mitch McConnell (R-Ky.), are vexed by Trump’s posture. At a minimum, they think he is needlessly creating a costly primary that will suck resources away from other targets on a map ripe for gains.

My guess is he’ll do the politic thing and steer clear of mentioning Ward, although he probably won’t be able to resist throwing a few jabs at Flake. Remember, even Trump’s own advisors are baffled that he’d tout “Chemtrail Kelli,” as that McConnell-aligned Super PAC calls her, when there are more credible Arizona Republicans who might pose a more serious primary challenge to Flake. The more Trump raises her profile, the more he risks muscling other contenders out of the race, leaving Flake with a better chance of winning than he might otherwise have. If anything, tonight would be a perfect moment for Trump to mention one of those other, more credible candidates and start muscling Ward out instead. Whatever happens, there’s a nonzero (significantly higher than zero, in fact) chance that we’re going to see a sitting president attack a sitting senator from his own party in his home state 15 months before a very tough reelection campaign. If Democrats end up with 51 seats after next year’s midterms and Flake ends up out of a job, remember this night as one that may have helped hand control to the other party.

On the other hand: Dude?

Trump is set to speak at 7 p.m. local time, which is 10 p.m. ET. Buckle up.