PORTLAND, Ore. — The mayor of Portland, Ted Wheeler, was left coughing and wincing in the middle of his own city on Wednesday night after federal officers deployed tear gas into a crowd of protesters that Mr. Wheeler had joined outside the federal courthouse.
Mr. Wheeler, who scrambled to put on goggles while denouncing what he called the “urban warfare” tactic of the federal agents in Oregon, said that he was outraged by the use of tear gas and that it only made protesters more angry.
“I’m not going to lie — it stings; it’s hard to breathe,” Mr. Wheeler said. “And I can tell you with 100 percent honesty, I saw nothing which provoked this response.”
He called it an “egregious overreaction” on the part of the federal officers, and not a de-escalation strategy.
“It’s got to stop now,” he declared.
But the Democratic mayor, 57, has also long been the target of Portland protesters infuriated by the city police’s own use of tear gas, which was persistent until a federal judge ordered the city to use it only when there was a safety issue. As Mr. Wheeler went through the crowd, some threw objects in his direction and others called for his resignation, chanting, “Tear Gas Teddy.”
Mr. Wheeler joined the crowd at the front of the protest, against a barrier around the federal courthouse. As a first volley of tear gas wafted over them, Mr. Wheeler stayed put, watching the actions of federal agents.
After another large wave of tear gas sent Mr. Wheeler away from the scene, some protesters mocked him, asking how it felt. Mr. Wheeler said that joining the protesters at the front of the line was just one way he was going to try to rid the city of the federal tactical teams.
“A lot of these people hate my guts,” Mr. Wheeler said in an interview, looking around at the crowd. But he said they were unified in wanting federal officers gone.
The mayor has called for federal agents to leave the city after they arrived to subdue long-running unrest. Dressed in camouflage and tactical gear and unleashing tear gas, federal officers have clashed violently with protesters and pulled some people into unmarked vans in what Gov. Kate Brown called “a blatant abuse of power.”
On Thursday, the inspectors general of the Departments of Justice and Homeland Security announced the start of an investigation into the actions of federal law enforcement agents responding to protests and civil unrest in Portland and Washington, D.C., after the police killing of George Floyd in Minneapolis.
In a letter to Congress and a public statement, Michael E. Horowitz, the Justice Department’s inspector general, said he and his counterpart would scrutinize the actions of law enforcement officials who cleared Lafayette Square, outside the White House, on June 1. Federal agents violently pushed protesters out of the square shortly before President Trump walked across it for a photo op in front of a church.
Mr. Horowitz and his counterpart at the Department of Homeland Security, Joseph V. Cuffari, said they would also examine the actions of agents in camouflage uniforms who have confronted protesters outside the federal courthouse in Portland. A video of two such agents seizing a protester and taking him away in an unmarked vehicle has sparked a furor.
Mr. Horowitz said he and his colleagues were undertaking the inquiries in response to requests by lawmakers, complaints his office had received, and a referral by the United States attorney in Oregon, Billy J. Williams.
“The review will include examining the training and instruction that was provided to the DOJ law enforcement personnel; compliance with applicable identification requirements, rules of engagement, and legal authorities; and adherence to DOJ policies regarding the use of less-lethal munitions, chemical agents, and other uses of force,” Mr. Horowitz wrote.
On the streets of Portland, some demonstrators called the mayor’s arrival at the protest scene a photo op. Sean Smith, who has been at the protests for weeks, said Mr. Wheeler, who also serves as police commissioner, needed to take more action to control the Portland Police Bureau and align with protesters.
“He should probably be out here every night,” Mr. Smith said.
Kenneth T. Cuccinelli II, the acting deputy secretary of homeland security, mocked Mr. Wheeler for his appearance at the protest, saying on Twitter that Mr. Wheeler had the choice to “stand with the rioters or stand with the rule of law.”
“He chose to stand with the rioters and STILL can’t appease them,” Mr. Cuccinelli wrote.
By early Thursday morning, with protesters still outside both the federal courthouse and the county justice center across the street, federal agents continued deploying tear gas; the Portland police repeatedly warned that city officers might also use it but did not do so.
The demonstrations, fueled by a wide array of grievances, including against police brutality, have rocked Portland for 55 consecutive nights and counting, persisting even as other protests across the country have waned.
The city has become a target of Mr. Trump, who has embraced a law-and-order message in his re-election campaign. While federal officers were deployed to Portland to purportedly quell unrest and protect federal property, their arrival has only galvanized the movement, with the numbers of protesters each night swelling into the thousands.
On Wednesday night and into Thursday morning, protesters gathered around a temporary fence that federal officers had erected during the day. They shot fireworks at the building, and some breached the fence. Federal officers, wearing camouflage and tactical gear, emerged to fire tear gas and less-lethal munitions, and to arrest those who breached the fence.
While the Trump administration has labeled the protesters “violent anarchists,” Mr. Wheeler decided to go into the crowd on Wednesday night for what he deemed a “listening session.” Even though people followed and cursed him, he spent three hours there.
At times he was jeered, such as when he told the crowd he would not promise to abolish the Police Department. Other times, he drew cheers, such as when he demanded that the federal government “stop occupying our city.”
“If they launch the tear gas against you,” Mr. Wheeler said, “they are launching the tear gas against me.”
Charlie Savage contributed reporting from Washington.