MADISON, Wis. (AP) — A central argument in Gov. Scott Walker's defense against allegations that he was part of a nationwide criminal scheme to break campaign laws is that those going after him are Democrats on a partisan witch hunt. But Walker ignores the fact that Republican prosecutors are also involved in the probe. The investigation was launched by a Democratic district attorney in Milwaukee and two judges have rejected arguments made by prosecutors and put the investigation on hold pending appeals. But the special prosecutor hired by a bipartisan group of district attorneys and nonpartisan panel of retired judges to lead the investigation is a Republican who says he voted for Walker. And the federal judge who issued a ruling halting the probe in May was appointed by a Republican president.