An outreach model that housed nearly 90% of people living outside in Pioneer Square earlier this year will be used across Seattle, Mayor Katie Wilson said Wednesday.

Her plan, contingent on a related effort to build up the city’s stock of shelter units, is the latest effort by a first-year mayor to get control of a complex issue that has foiled a string of Seattle mayors before her — as well as cities across the nation.

Wilson said she recognized the factors that could upend her plan — from local opposition to the global economy — but said a coordinated effort among the city, businesses and service providers was a combination that she believed would finally work to house the thousands of people who sleep outside in the city.

“For years, mayors and their teams have come and gone, but the moral outrage and homelessness in one of the wealthiest cities and richest countries in the world has only worsened,” she said. “Homelessness is not a natural occurrence. It is a policy failure.”

Wilson delivered few details. She declined to share where the model would first be replicated, or how much the plan would cost the city in total. But with with an array of City Council members, business leaders and service providers standing around her, she had already won broad support to try something new.

Overall, Wilson’s plan will overhaul how the city connects people to shelter, so those on the streets with the greatest challenges get into shelters or housing that match their level of need. She wants to prioritize people with mental health or addiction issues and people living in public areas.

“Our public parks and public sidewalks belong to the public,” Wilson said, adding that the city will still clear encampments at its current pace. “They should be kept open and usable for their intended purposes.”