Wisconsin Gov. Scott Walker says thousands of internal documents released publicly this week are "old news."
Walker also added that while that investigation is closed, New Jersey Gov. Chris Christie's problems are "just beginning."
Both Republicans are considering 2016 presidential runs.
Walker addressed the issue for the first time publicly during Saturday's meeting of the National Governors Association in Washington.
The released documents suggest Walker's former aides routinely mixed campaign and official Milwaukee County business. Walker was the county executive at the time he was running for governor. Six former aides and associates have been convicted, but Walker has not been charged with any wrongdoing.
State and federal authorities are probing the Christie administration for days-long traffic gridlock at the George Washington Bridge, possibly to retaliate against a political adversary.