Two McCain offices evacuated after letter threat Thu Aug 21, 2008 8:45pm EDT By Keith Coffman DENVER (Reuters) - Two offices of John McCain's U.S. presidential campaign, in Colorado and New Hampshire, were evacuated on Thursday, and several staffers were hospitalized, after threatening or suspicious envelopes arrived in the mail, one with an unidentified white powder. The first parcel, described as containing an unspecified threat and a powdery white substance, was opened by a staff member at the campaign's Centennial, Colorado, office, near Denver, at about 3 p.m. local time, U.S. Secret Service spokesman Malcolm Wiley said.