Zach Silk, spokesman for Washington United for Marriage, says:

"We'd love people to show up at 4 o'clock at the state capitol. You can look for our Washington United for Marriage people, who will have t-shirts and clipboards—and we will work with you to make sure that you have the best view of the hearings. Either you can go to the senate gallery, or if the senate gallery's full there's going to be a lot of viewing within the capitol."

With 25 committed yes votes—just barely enough to pass the bill—Silk is predicting "an historic moment" for Washington State.

In reality, though, it may take more than a moment. I'm told the process could drag on into the night as various state senators speechify, use sneaky parliamentary tactics to try and derail the bill, and preen for the TVW cameras.

I'll be down there, and I'll let you all know what I'm seeing.