A threatening email has derailed one of the Portland Rose Festival's signature events, and spurred new debate about the ongoing political protests in Portland.

Organizers of the 82nd Avenue of Roses Parade announced Tuesday that the event will be canceled, for fear that the east Portland parade could be disrupted by "the type of riots which happen in downtown Portland."

Originally scheduled this Saturday, April 29, the parade is meant to highlight the local community and businesses along Southeast 82nd Avenue, aiming to turn around the negative perception many people have of the area. It started in 2007 and has since become a popular event on the Rose Festival calendar.

This year's parade was once again set to feature the Multnomah County Republican Party as one of the many groups slated to march, but that inclusion drew ire from some of the city's left-leaning protest groups.

At least two protests were planned for the day of the parade, one by Oregon Students Empowered and another by Direct Action Alliance. Both events were mentioned in an email sent to parade organizers on Saturday, threatening to shut down the event with hundreds of protesters in the street.

"You have seen how much power we have downtown and that the police cannot stop us from shutting down roads so please consider your decision wisely," the anonymous email said, telling organizers they could cancel the Republican group's registration or else face action from protesters. "This is non-negotiable."

The parade is organized by the 82nd Avenue of Roses Business Association, a part of the neighborhood business organization Venture Portland. Representatives from neither organization returned calls for comment.

The cancelation isn't necessarily a win for the protest groups. Jacob Bureros, an organizer with the Direct Action Alliance, said the organization - which intended to speak out against fascism and white supremacy during the parade - is sad to hear the news.

"We are disappointed that the parade was canceled," he said. "We're members of this community and this is an awesome parade."

James Buchal, chairman of the Multnomah County Republican Party, said his group was ready to march despite the protesters. He said the party had no hand in cancelling the event, and was taken by surprise when they heard the news. After seeing the email last weekend, they had no plans to back out.

"We weren't willing to just walk away quietly," he said. "The next thing we knew the whole thing was canceled."

Organizers pulled out after contacting Portland police, according to Rich Jarvis, spokesman for the Rose Festival Foundation. When police said they couldn't offer any additional security for the parade, organizers decided to cancel it due to safety concerns.

"The showdown was imminent," Jarvis said. "They were boxed into a corner, they simply had no choice. In order to avoid a violent outbreak, they had to cancel the parade."

He said the festival has received other threats from local protest groups, who voiced displeasure about the annual Fleet Week event in particular. While it would be significantly more difficult to disrupt an event of that magnitude, it's within the realm of possibility.

"It's all about safety for our fans, first and foremost. If we can't provide safety for our fans, there's no use in trying," Jarvis said. "Our official position is we're extremely sad about this."

--Jamie Hale | jhale@oregonian.com | @HaleJamesB