Amid blistering criticism from all sides after the killing of a Trump-supporting protester in Portland on Saturday night, Mayor Ted Wheeler denounced President Donald Trump for stoking divisions and accelerating violence in this city.

At a press conference in Portland City Hall, Wheeler addressed Trump directly.

"Do you seriously wonder, Mr. President, why this is the first time in decades that America has seen this level of violence?" he asked. "It's you who have created the hate and the division. And now you want me to stop the violence that you helped create. What America needs is for you to be stopped so that Americans can come together."

Asked by a reporter about Trump's comments that he wasn't surprised by a killing in Portland, Wheeler reacted with visible anger.

"I's appreciate that either the president support us or stay the hell out of the way," Wheeler said. "Of course he's not surprised. He encouraged them to come into our city."

Trump immediately struck back on Twitter with a threat to send more federal law enforcement into Portland.

"Ted Wheeler, the wacky Radical Left Do Nothing Democrat Mayor of Portland, who has watched great death and destruction of his City during his tenure, thinks this lawless situation should go on forever," Trump wrote. "Wrong! He would like to blame me and the Federal Government for going in, but he hasn't seen anything yet."

That led to the remarkable sight of Wheeler responding to Trump's tweets in real time as reporters read them aloud in what amounted to a socially distanced debate between the Portland mayor and the U.S. president.

"It's classic Trump," Wheeler said. "Mr. President, how can you think that a comment like that is in any way helpful? Let's work together. Wouldn't that be a message? Donald Trump and Ted Wheeler working together."

The strange dialogue came amid shock and rage following the shooting death of a conservative protester who came to Portland to provide security for a truck caravan supporting President Trump.

The president jeered on social media today that Wheeler had failed to control violence in the city, while five progressive groups called on the mayor to resign.

Shortly before 9 pm Saturday night, a man was killed by a gunshot to the chest outside a parking garage on Southwest 3rd Avenue. Photos of the scene showed he was wearing a hat with the insignia of Patriot Prayer, a protest group that marches in support of Trump.

This morning, Patriot Prayer organizer Joey Gibson confirmed the slain man was a "friend and supporter" of the conservative protest group, which for three years has visited Portland for marches and brawls with anti-fascists.

The politically freighted killing sent a spike of fear through the city, which in recent weeks has seen nightly protests of police brutality turn into standoff between Black Lives Matter demonstrators and right-wing counterprotesters.

"For the last several years, and escalating in recent months, President Trump has encouraged division and stoked violence," Gov. Kate Brown said in a statement today. "It happened in Charlottesville. It happened in Kenosha. And now, unfortunately, it is happening in Portland, Oregon."

The dynamics of protest violence in Portland can be dizzying. But since federal police withdrew from Portland's protests, confrontations between leftist protesters and local police have grown increasingly harsh. The sight of left-wing protesters repeatedly defacing buildings, such as the Portland police union headquarters, has enraged conservatives. That's led to several right-wing rallies in Portland, a massive downtown brawl a week ago, and one pro-Trump protester firing two gunshots toward a crowd of racial justice demonstrators.

Police rarely intervened in these clashes. Wheeler attempted to hit a reset button on Thursday, calling for the city to "rise up" to denounce violence and clean up downtown graffiti. Instead, a squadron of trucks waving Trump flags rolled into downtown—and a person connected to that squadron died.

That context may explain why five progressive and civil rights groups called for the mayor's resignation on Sunday morning. (The groups included the Oregon chapter of the Council on American-Islamic Relations, the Oregon Justice Resource Center, the Portland Democratic Socialists of America, NextUp Action Fund, Portland's Resistance, and PopMob, an anti-fascist organization.)

"[Wheeler] has spent his entire tenure pretending he occupies the middle ground between the far left and the far right when in reality, he and his police have sheltered and encouraged far-right violence," the groups said in a statement. "He has exacerbated tensions in Portland, giving fuel to right-wing vigilante violence who, in answering the mayor's call to 'rise up,' felt justified in their violent actions."

Wheeler's opponent in the November election, Sarah Iannarone, expressed horror and frustration with political leaders, but did not explicitly blame the mayor.

"While facts are limited, what we do know is that one individual is dead at the hands of another on the streets of Portland," she wrote. "This violence is unacceptable, and I condemn it in absolute terms. Unfortunately, this violence was predicted by many but preventable by those in positions of power."

President Trump spent the early hours of Sunday morning taunting Wheeler on Twitter. He retweeted an account that mocked the mayor: "Ted Wheeler is the useless fucking idiot and comic relief that gets everyone killed in every disaster movie."

"Tone down the language, but TRUE!" wrote the president.

Democratic presidential nominee Joe Biden struck a different tone.

"We must not become a country at war with ourselves," Biden wrote. "A country that accepts the killing of fellow Americans who do not agree with you. A country that vows vengeance toward one another. But this is the America that Trump wants us to be, the America he believes we are."

Portland Police Chief Chuck Lovell said during the City Hall press conference Sunday afternoon that the Portland Police Bureau attempted, without success, to keep Saturday's caravan of Trump supporters on interstate highways and not allow them onto surface streets in downtown.

Lovell cautioned, however, against assuming the killing was politically motivated.

"It could have just been a skirmish between two small groups," he said, "or a conflict between two individuals."

Not for the first time, Wheeler this afternoon implored people from outside of Portland to refrain from entering the city seeking retribution for the death and asked Portlanders to also avoid street standoffs: "Let's not take the bait."

Wheeler said he would not resign. He did not otherwise respond to local calls for him to step down.

"We all saw this coming. I've stood at this podium I don't know how many times and said that we must denounce the violence. But the president has a role to play as well in understanding systematic injustices. He has an opportunity to uplift us, and instead he chooses to play petty politics.

"I have said my greatest fear is that somebody would die," Wheeler added. "And now somebody has. I as the mayor am accountable.…This is a long road ahead of us. But we know that the dead end is violence. That is a dead-end street."

Wheeler concluded on a note of regret.

"It's hard for me to stand here, with a human being dead, and say that we did everything we possibly could," he said. "I can't make that statement. It would be preposterous of me to do so."