At issue is whether Walker knew aides who worked for him when he was Milwaukee County executive were flouting those campaign laws. His opponents are using more than 25,000 new documents from former aides released last week to make the case that he did.
But Walker said charges that he knew of his aides' actions are "absolutely not true."
"Plain and simple, it's old news," Walker, who is facing re-election, said on "Fox News Sunday."
"It's one of those things where [opponents] want to keep pushing this issue into forefront because, in the end, the folks running against us can't counter our positive message when it comes to the economy and creating budget surpluses," he said.