Christie, who also chairs the Republican Governor's Association, says the attacks against Walker are coming from his political opponents because he's trying to bring change to the state.
Both Republican governors are potential 2016 presidential candidates. Christie says he spoke to Walker Friday to offer support.
Walker is defending against newly released court documents in which prosecutors put him at the center of a nationwide scheme to evade campaign-finance rules and collaborate illegally with conservative groups. No charges have been filed.
Christie, who's had a bridge-closing scandal to contend with, calls Walker "a good man" and says he stands with him.