Who says so? Rush Limbaugh? Fox? How about MSNBC?
UPDATE: First, watch this video of Chris Matthews:
As Politifact reported, the unions were split on their support of candidates. Then-candidate Walker got the endorsement of two police and fire unions with a combined total membership of 2,275; his opponent received the endorsement of police and fire unions with a combined membership of 14,000- more than six times as many. And anyone even loosely following the story knew that even before PolitiFact ran it; I read it last week. So for Chris to ask the question he did, phrased the way he did, when he did, I see only two possible explanations: either he just reads activists' faxes without fact checking or vetting them, or he is knowingly attempting to deceive. I'm not sure which is worse.