There is no shortage of controversies surrounding Trump's appearance tonight in Phoenix that could turn what is supposed to be a peaceful political rally into complete chaos. With Trump's reaction to the Charlottesville tragedy still fresh in the minds of political activists on the left, there are expected to be as many protesters outside the Phoenix Convention Center as there are inside watching the President's speech. Sprinkle on top of that the fact that Trump could comment on a potential pardon of Sheriff Joe Arpaio and/or blast Arizona Senators John McCain and Jeff Flake and you have all the ingredients of another national disaster in the making.

As The Hill points out, the Phoenix Police Department has planned for "maximum staffing" during Trump's visit and the FBI and DHS are also coordinating on the event.

Political leaders and law enforcement officials in Arizona are on high alert ahead of President Trump’s campaign rally Tuesday night in Phoenix. The big question is whether there will be more supporters of Trump inside the Phoenix Convention Center, which holds 29,000, or protestors outside. Phoenix Police Chief Jeri Williams said in a statement that her force will have “maximum staffing during the visit.” The department is “working 24/7 with our partners to ensure all of our resources are in place,” Williams said. Stanton said the city is committed to keeping everyone inside and outside the arena safe. “The Phoenix police is always professional and the FBI and Department of Homeland Security have been great about coordinating with local law enforcement,” former Arizona GOP chairman Robert Graham told The Hill.

Meanwhile, Phoenix Police Chief Jeri Williams offered the following warning to protesters:

"There is a distinct difference between voicing your first amendment rights and committing unlawful acts. As always, free speech will be supported but criminal conduct will be immediately addressed."

Of course, racial tensions arising from Charlottesville are only part of what makes tonight's rally a recipe for disaster. Some fear that Trump could use the occassion to announce that he'll pardon Maricopa County's controversial former Sheriff, Joe Arpaio, who was found guilty of racially profiling hispanics and sentenced to jail time.

The president has mused publicly about pardoning controversial former Maricopa County Sheriff Joe Arpaio, an early Trump supporter who was found guilty of racially profiling Latinos. Arpaio, who was prosecuted and convicted of racial profiling by former President Obama’s Justice Department, is a well-known and controversial figure in Phoenix. Democrats are warning that a public pardon at a campaign rally would stoke racial tensions at a time when the nation is on edge. Stanton said a pardon would “enflame emotions and further divide our nation,” while Rep. Ruben Gallego (D-Ariz.) said Arpaio “shouldn’t be let off the hook for his crimes” just so Trump can win “some bonus points with his most racist supporters.” But some Republicans in the state believe Arpaio was railroaded by the Obama Justice Department and are eager to see his name cleared. Rep. Andy Biggs (R-Ariz.) released a statement on Monday calling Arpaio’s conviction “the culmination of a political witch hunt by the Obama administration to sideline and destroy a formidable opponent.” "Sheriff Arpaio has been a faithful servant of this nation for over six decades,” Biggs said. “He should be allowed to live out the rest of his days in peace and confidence that his efforts were not in vain.”

And then there is Trump's growing fued with Arizona Senator Jeff Flake whose book “Conscience of a Conservative,” which argues that Republicans must reclaim the soul of their party from Trump, apparently didn't sit well with the White House.

Speculation is rampant among political operatives in Arizona about whether Trump will meddle in the state’s 2018 primary, where Flake has attracted a primary challenger in state Sen. Kelli Ward (R), who will attend the rally — though not as a guest of Trump’s. The president has not made an endorsement in Flake’s race but has tweeted support for Ward, a former state senator who is not viewed as a credible challenger by many establishment Republicans. A super PAC supporting Ward’s bid has received a $300,000 donation from conservative mega-donor Robert Mercer and several operatives from a pro-Trump outside group have peeled off to work for her.

Great to see that Dr. Kelli Ward is running against Flake Jeff Flake, who is WEAK on borders, crime and a non-factor in Senate. He's toxic! — Donald J. Trump (@realDonaldTrump) August 17, 2017

Finally, of course, we all know how Trump feels about John McCain who cast the deciding vote to kill the Obamacare repeal bill just before the August recess.

The fireworks are set to start at 7pm local time...