WASHINGTON (AP) -- First it was Chris Christie, humbled by members of his staff who impeded access to a bridge from New Jersey into Manhattan in an apparent act of political retribution.
Now it's Scott Walker, who prosecutors in Wisconsin believe acted criminally by coordinating the fundraising and spending of outside conservative groups.
They are two of the nation's highest-profile Republican governors, and both have hopes for the White House in 2016. And in a midterm election year, when would-be presidential candidates like to showcase their accomplishments, they are instead dealing with the fallout of controversies at home.
"The newest front in electoral politics is to try and dirty up candidates before they can run by starting investigations," said Steve Duprey, New Hampshire's former Republican state chairman and current Republican National Committeeman, who called it a "disturbing trend on both sides of the aisle."
For Christie, the story has already shifted to focus on his recovery. He and his advisers believe the worst of his political troubles are behind him, in part because no evidence has come to light that he was personally involved in the bridge closure that prompted him to fire his top political adviser and deputy chief of staff.
For Walker, the troubles may be just beginning. Documents released Thursday put the polarizing governor himself at the center of an investigation into campaigns in 2011 and 2012. Also named were his two closest political advisers, one of whom is his former chief of staff.
Walker defended himself Friday in a television interview. "This is not new news; it's just newly released yesterday. Documents were opened, but no charges. Case over," he said on Fox News.
Walker said there was "no doubt" that he's being attacked unfairly much in the same way Christie was earlier in the year.
"The media jumps on this. Some on the left spin this. You've got your detractors out there trying to claim there's something more than there is," he said.
That investigation has yet to yield any charges, and Walker and others argue the activities deemed by prosecutors as illegal aren't governed by the state's election laws -- a question that's now pending before a federal appeals court.
But unlike Christie, whose next appearance on a ballot may be part of the 2016 campaign, Walker will face voters at home before he can turn his attention to a bid for the White House.
"He's got to win in Wisconsin this year to be a viable presidential candidate," said Doug Gross, a Republican fundraiser and veteran adviser to presidential candidates in the early-voting state of Iowa.
That Christie won re-election last year has given him the space to first offer contrition for the actions of his staff and then slowly re-emerge as a potential presidential candidate. For the past five months, he's traveled the country raising millions of dollars for the Republican Governors Association as its chairman. It's only in the past few weeks that he's stepped up his public appearances, returning to late-night television and even delving into foreign policy.
On Friday, after addressing a conference of religious conservatives in Washington, Christie made his first trip to the early presidential primary state of New Hampshire since the bridge allegations turned into national headlines. He dismissed the idea that he was warming up for a presidential run -- he was campaigning with the state's Republican gubernatorial candidate -- and offered support to Walker.
"I have complete faith and confidence in Scott Walker," Christie said. "He's got great integrity."
Walker rose to prominence nationally by leading the effort in Wisconsin to effectively end collective bargaining for most public workers, an act that led to a tightly contested election in 2011 in which Republicans narrowly retrained control of the Wisconsin state Senate and a 2012 recall election in which he beat back an effort to remove him from office.
State prosecutors said in the documents made public Thursday that during those elections, Walker, former chief of staff Keith Gilkes, top adviser R.J. Johnson and campaign operative Deborah Jordahl illegally discussed fundraising and coordination with national political groups and prominent Republican figures, including GOP strategist Karl Rove.
Walker dismissed the findings, pointing to the decisions of a state and a federal judge who have ruled that no violations of the law occurred. "I'm not asking people to take my word for it, or political allies'," Walker said Thursday.
But Walker's campaign aides declined to discuss the potential political impact of the allegations, and Democrats remain eager to take on Walker in a race for governor.