The violent protests of the last three months in Portland, Ore., escalated on recently into a right-left confrontation that resulted in one man shot dead in the streets. This is what happens when political leaders fail to perform the most basic responsibility of government to protect innocent lives and property.

The main failure here lies with Portland Mayor Ted Wheeler and Gov. Kate Brown, who have consistently indulged the rioters. Every night for more than 90 days, Black Lives Matter and Antifa protesters have demonstrated in Portland. Many are peaceful, but a hard core have repeatedly attacked police and burned buildings.

When President Trump sent federal law enforcement agents to Portland this summer to protect federal buildings, the mayor and Governor blamed Mr. Trump for the violent clashes. But when federal agents stood down, the violence continued against Portland police and property. Mr. Wheeler issued an open letter rejecting Mr. Trump’s latest offer of federal help to restore order.

“We don’t need your politics of division and demagoguery. Portlanders are onto you. We have already seen your reckless disregard for human life in your bumbling response to the COVID pandemic. And we know you’ve reached the conclusion that images of violence or vandalism are your only ticket to reelection,” Mr. Wheeler wrote.

Yet his city is the one burning and where someone has now been killed. Mr. Wheeler, Gov. Brown and state lawmakers have hamstrung police by limiting anti-riot tactics. At a press conference the Portland police chief said his department lacked the resources to separate the fighting factions, but the feckless Mr. Wheeler offered little more than a plea against violence and rhetoric about reform to address racial injustice.

That hasn’t stopped Democrats from blaming Mr. Trump for the violence. Democrats spent their convention never mentioning the urban violence, but after the Kenosha riots and the GOP convention, this has become a political liability. So they’re pivoting to blame Mr. Trump and claim that “his America” is causing it. As if Trump supporters belong to Antifa and dominate U.S. cities. ....

Mr. Trump should tell his supporters to stay away from Portland, Kenosha, Wis., and other cities where rioters reign. ...

Vigilantism isn’t the cause of the current urban violence, but it could become one result of the failure to control violence. Americans have watched for weeks as rioters burned and looted businesses that people spent a lifetime building. Yet mayors like Ted Wheeler have let it happen. Inevitably, average citizens will move to defend themselves if elected officials won’t protect them. The proper place to do that is at the ballot box, however, not in the streets with guns.

An editorial from the Wall Street Journal.