Virginia Gov. Bob McDonnell's Boy Scout image is taking a beating in his final year in office, and hopes of a national political career appear to be fading with the news that the FBI and a federal grand jury are investigating the governor's ties to an influential campaign donor.

Talk of McDonnell as a potential 2016 Republican White House candidate — VP at a minimum — has all but ceased. And while his approval ratings in Virginia remain an enviable 59 percent, it's unclear how long the cloud of a federal investigation will hang over him or whether it will do any irrevocable political damage.

Federal authorities are looking into McDonnell's relationship with Star Scientific CEO Jonnie Williams. Williams for years showered McDonnell with campaign contributions and gifts, including vacations and use of his Ferrari. Williams also paid the $15,000 catering bill for the wedding of McDonnell's daughter, something the governor failed to report for two years.

In turn, Virginia's first family feted Williams at the executive mansion in August 2011 and, around the time of their daughter's wedding, First Lady Maureen McDonnell flew to Florida to promote Anatabloc, a tobacco-based supplement Star Scientific hoped would be a major money-maker.

McDonnell insists that the supplement maker, which is suing the state over unpaid taxes, received no special considerations. He didn't report the catering bill, he said, because state disclosure laws doesn't cover gifts given to family members.

The unfamiliar negative publicity is clearly taking a toll. The normally media-friendly McDonnell was rushed out of a Northern Virginia event by his handlers earlier this month after news broke that a Republican state lawmaker was called to appear before the investigating grand jury.

"Unfortunately, I cannot comment," McDonnell told a Norfolk radio station. "I've never commented on any potential or possible investigations."

Adding to McDonnell's troubles is the embezzlement trial of his former mansion chef, Todd Schneider, who claimed in court papers that McDonnell and his family used the state-funded mansion as a personal pantry.

McDonnell came to the national attention when he won the 2009 governor's race just a year after President Obama had won Virginia. Months later, McDonnell was delivering the GOP response to Obama's State of the Union address and, later, traveling the country raising money for other Republicans running for governor.

He was considered, but didn't get, the vice presidential slot on the 2012 Republican ticket, and he missed out on a likely cabinet post with Mitt Romney's loss to Obama.

McDonnell rebounded somewhat this year by winning legislative approval for a historic transportation-funding package, but that won't be enough if the FBI probe produces any charges.