PORTLAND, Ore. -- Vandals sprayed graffiti on Keller Auditorium in downtown Portland ahead of a visit by former Vice President Al Gore.

A spokeswoman for the auditorium said there were several areas where graffiti was found by police. She said two exterior walls were hit as well as sidewalks and the entrance to the building.

One message said, "Change the system, not your light bulbs." Another message said, "Don't buy false solutions."

Gore discussed climate change at the auditorium Wednesday night. The auditorium spokeswoman said the graffiti is likely related to Gore's visit.

"It's under investigation by police and they haven't shared any of that information with us," she said. "But that's the assumption that it's related to tonight's speaker."

A group named Americans for Prosperity held an event across the street from the auditorium to expose what they call the extreme economic costs behind federal climate change policies. However, the group condemned the overnight vandalism.

Representatives of the Portland Center for the Performing Arts issued a statement saying they are disappointed that vandals would deface a community treasure like Keller Auditorium.

Both anti and pro-Gore rallies are scheduled Wednesday evening.

Gore authored the book "An Inconvenient Truth." The best-seller touched on the threat of and the solutions to global warming. He is now promoting his new book entitled "Our Choice." His lecture Wednesday night shares the same name.

Keller Auditorium sits on the corner of 3rd Avenue and Clay Street near Portland State University.

Slideshow: Auditorium Vandalized Ahead Of Al Gore Visit

Auditorium Vandalized Ahead Of Al Gore Visit

Aerial View: Auditorium Vandalized Ahead Of Al Gore Visit