Federal officials told Portland Mayor Ted Wheeler today they will not revoke a permit for an alt-right "free speech" rally planned for downtown Sunday, meaning the event will proceed in a city still reeling from the slaying of two people, allegedly by a white supremacist.

Wheeler had asked the federal government to revoke the permit for Joey Gibson and his alt-right allies to use Terry Schrunk Plaza on June 4. Wheeler wanted to block the rally, but the park across from Portland City Hall is federal property.

The United States General Services Administration today responded to Wheeler: No.

"All rules and regulations were followed by the applicant for the permit, including the timeframe for review," the GSA said. "Since the permit was lawfully obtained to assemble at this federal location, GSA has no basis to revoke the permit."

But the GSA did make a concession to Wheeler: It will send Federal Protective Services officers to patrol the event.

Wheeler also promised a massive police presence—a sign that the city's approach to alt-right protesters, which has previously been conciliatory, has shifted.

"There will be local and federal law enforcement on the ground to ensure everyone has the right to express their beliefs and to protect everyone's safety," Wheeler says. "I urge everyone participating to reject violence. Our city has seen enough."

Jeremy Joseph Christian, who described himself as a foot soldier of a new fascist empire, is accused of murdering two men and wounding another who intervened May 26 as he harassed two teenage girls with an anti-Muslim screed on a Portland MAX train. Multiple witness accounts say he cut the throats of three men who confronted him.

Related: Who radicalized Jeremy Christian? Extremist groups rush to distance themselves from a double-slaying suspect.

Wheeler on Monday asked the feds to cancel the rally, organized by Vancouver, Wash.-based blogger Joey Gibson and expected to draw some of the biggest celebrities on the "alt-right," a collection of extremists and provocateurs who seek violent confrontations with leftists.

The mayor's efforts were immediately criticized by civil-liberties watchdogs as a violation of the First Amendment. Today, Wheeler defended his actions.

"I am a firm supporter of the First Amendment, no matter the views expressed," he said in a statement. "I believe we had a case to make about the threats to public safety posed by this rally at this place and at this time. My job is to protect the safety of everyone… protesters, counter-protesters, and bystanders alike."

Gibson has told WW he intends to go forward with his event, and disavowed Christian. Multiple left-wing groups, including labor unions, have vowed to peacefully confront the alt-right Sunday.

Another event planned by Gibson, a June 10 march against Muslim Sharia law, announced today it is canceling its Portland protest and concentrating on a Seattle protest.

The full response from the GSA reads as follows:

“The U.S. General Services Administration Northwest/Arctic Region received a request from an applicant on May 10 to assemble at the Terry Schrunk Plaza in Portland, OR, from 2-4 p.m. Sunday, June 4. The applicant submitted the appropriate form (form GSA3453), which includes a terms and conditions section. The form can be found here. GSA reviewed the application, and in accordance Title 41 of the Code of Federal Regulations part 102-74, Subpart D, approved it May 15. All rules and regulations were followed by the applicant for the permit, including the timeframe for review. Since the permit was lawfully obtained to assemble at this federal location, GSA has no basis to revoke the permit. GSA and Federal Protective Services (FPS) are working closely with the City of Portland law enforcement and the Mayor’s Office to prepare for the June 4 event. The City Of Portland, GSA, and FPS ask those who attend the event to assemble safely and allow all to exercise their constitutionally protected rights.”

The Mayor's full response reads as follows:

“Portland has a proud history of protest. I am a firm supporter of the First Amendment, no matter the views expressed. I believe we had a case to make  about the threats to public safety posed by this rally at this place and at this time. My job is to protect the safety of everyone… protesters, counter-protesters, and bystanders alike. There will be protests and counter-protests this weekend in Portland. We have reached out to the organizers to call upon them to exercise common sense and to help us keep the peace. There will be local and federal law enforcement on the ground to ensure everyone has the right to express their beliefs and to protect everyone’s safety. I urge everyone participating to reject violence. Our city has seen enough.