What did Donald Trump do today?

He called for violence to help keep him in power.

Trump has no realistic path to victory without Pennsylvania, where native son Joe Biden has held a small but consistent lead throughout the entire race. His campaign has fought hard (and with some success) to prevent likely Biden votes from being cast or counted in the state, mostly through attacks on absentee ballots or the way they're delivered. 

In the last few days of the campaign, Trump has fixated on a Supreme Court decision allowing—at least for now—absentee ballots postmarked by Election Day to be counted if they reach election offices in Pennsylvania by November 6. (Many other states allow ballots mailed on or before Election Day to count even if they reach the offices much later than that.)

Today, he declared that this decision was "physically dangerous" because it would lead to "violence in the streets." Of course, only Trump's supporters would have any reason to react violently to him losing the election.

A few things are worth noting. First, Trump has explicitly refused to guarantee a peaceful transition of power if he loses. No other president or presidential candidate has ever done this.

Second, even though American elections have been entirely free of partisan violence since the end of the Jim Crow era, there is one example Trump might have in mind: the so-called "Brooks Brothers riot" of 2000. A group of Republican political aides were paid to disrupt a critical recount in Florida before a court-imposed deadline, and succeeded. Punches were thrown, but no one was seriously hurt. The riot helped cement in place George W. Bush's microscopic margin of victory in Florida.

That riot was organized by Trump's own political fixer, Roger Stone, who was later convicted of obstruction and witness tampering related to the Russia investigation.

Finally, Trump has show a real talent for inciting his followers to violence. He's encouraged his supporters to beat up protestors at his rallies (and then stiffed them on the legal bills he promised to cover if they did). But he's also carefully cultivated relationships with genuinely violent groups like the Proud Boys, who he told last month to "stand by" for the moment, or the white nationalists who organized the the "Unite the Right" rally in Charlottesville where a counter-protestor was killed. He's also won the loyalty of normally anti-government "militias" by defending members accused of murder or encouraging them to "liberate" themselves from state politicians he doesn't like. 

The tally of violent crimes that can be traced back to Trump's incitement includes the recent kidnapping plot against Michigan Gov. Gretchen Whitmer (which also involved the planned murder of police officers), pipe bombs mailed to Trump's supposed enemies in the media and the Democratic Party, a similar plot against Democratic politicians carried out by a Coast Guard officer, the racial harassment and attempted kidnapping of Hispanic-Americans by a self-described Nazi Trump supporter, and literally dozens of death threats and assaults against journalists, women, and racial minorities carried out in Trump's name.

Why is this a problem?

• You either have democracy, or a leader trying to hold onto power through violence against his own citizens—not both.