"Anyone know more about this? Was he too rudely antiwar?"
Doesn't appear to be the reason: "In Ohio a leading backer of the Woolsey amendment, Representative Sherrod Brown, has entered the Senate primary race against Paul Hackett, the Iraq War veteran who was bluntly critical of Bush's handling of the war during a losing race this past summer for an open House seat. In his House race Hackett surprised many fans of his anti-Bush remarks by opposing a timeline for withdrawal, and he has since disturbed war critics by dismissing the Congressional push for a timeline as 'absolutely ludicrous.' There is no such ambiguity with Brown. He was an outspoken foe of the 2002 resolution authorizing Bush to use force in Iraq, and since the start of the war he has written House letters demanding answers from the Administration about the misuse of prewar intelligence, co-sponsored withdrawal resolutions and regularly read letters from antiwar constituents--particularly members of military families--into the Congressional Record."
http://www.mattbrown.org/index.php?option=com_content&task=view&id=125&Itemi d=146
-- luke