Well, let's see...Virginia's current statewide elected officials are: Jim Webb, Mark Warner, Tim Kaine, and Bill Bolling. I doubt it's Bolling (ha), and I believe the other three already have endorsed Creigh Deeds. Which leaves...??? Got me.
UPDATE: If it's a former statewide elected official, teacherken suggests it could be Tim Kaine's father in law, former Gov. Linwood Holton. Another possibility would be John Warner, but I strongly doubt that. My money's on Linwood Holton.
UPDATE #2: I was just thinking, it could be Chuck Robb...