The planning agency that decides how federal and state dollars are spent on transportation in Greater Portland will hold a forum Thursday to ask the public for guidance on how to spend that money over the next two decades.

Some of the key issues include whether the region should extend public transportation to the suburbs, or instead focus on using its limited funds to maintain the current transit system. Also, should land-use and transportation planning be coordinated to encourage people to live in compact villages and town centers, where they can be more easily served by public transit?

The Portland Area Comprehensive Transportation System is creating a 20-year plan for spending more than $400 million in federal and state funds in the region, which includes 18 municipalities. The agency’s policy committee is scheduled to approve the plan next fall.

The agency has held five forums in the region. Thursday’s forum, at 5 p.m. at Merrill Auditorium Rehearsal Hall in Portland City Hall, will be the last.

The agency also plans to conduct a telephone poll in March.