AP link.
Sheehan said she will run against the San Francisco Democrat in 2008 as an independent if Pelosi does not seek by July 23 to impeach Bush. That's when Sheehan and her supporters are to arrive in Washington, D.C., after a 13-day caravan and walking tour starting next week from the group's war protest site near Bush's Crawford ranch.
July 23rd? This is sooner than, for example, the Sept 15 March on Washington being organized by the impeachbush.org group.
Momentum!
See also: Linda Milazzo's excellent diary, calling for action and outrage.
UPDATE: Lisa Lockwood comments below on the Caravan ("Summer of Love '07") that Sheehan intends to lead to DC, including the text of an email Sheehan sent her a week ago, describing the march, and the possibility of a sit-in in Conyer's office.