KOMO-TV is hosting the debate at Fisher Plaza and will carry it live at 9 p.m. The debate also will be streamed live at komonews.com.
Democrat Jay Inslee and Republican Rob McKenna will be questioned by a panel of TV reporters and anchors during the one-hour debate.
Polls indicate the two candidates are in a close race to replace outgoing Gov. Chris Gregoire.
Inslee and McKenna will meet in their final debate on Oct. 16.