(CNN) The revelation that Virginia Gov. Terry McAuliffe is facing a federal investigation related to campaign donations could complicate Hillary Clinton's effort to win the crucial swing state and its 13 electoral votes in November.

The ties between McAuliffe and the Clinton family run deep -- both personally and professionally.

McAuliffe often refers to former President Bill Clinton as his best friend. He served as Clinton's handpicked chair of the Democratic National Committee. Hillary Clinton was an early and enthusiastic supporter of McAuliffe's run for governor in 2013, holding several rallies and helping him raise money.

The personal bonds are only part of the story. Several of McAuliffe's key campaign staffers have graduated to the Clinton campaign and the overall infrastructure of McAuliffe's 2013 run was thought to be a test case of how Clinton could win there in 2016.

CNN reported Monday that McAuliffe is the subject of an ongoing investigation by the FBI and prosecutors from the Justice Department's public integrity unit are thrusting him back into the spotlight. U.S. officials briefed on the probe say the investigation dates to at least last year and has focused, at least in part, on whether donations to his gubernatorial campaign violated the law, the officials said.

McAuliffe has denied any wrongdoing and has said that federal investigators have yet to contact him regarding the matter, telling reporters Tuesday "... investigations happen, no one's alleged any wrongdoing on my part."

He has not been accused of any wrongdoing.

McAuliffe's victory in Virginia did not come easy. He narrowly beat the controversial Ken Cuccinelli, then the state's attorney general, by less than 2 percentage points. McAuliffe's narrow victory came despite outspending Cuccinelli by close to $18 million.

"In 2013, the race for governor was not a campaign against Terry McAuliffe. It was campaign against the Clinton machine," said Chris LaCivita, a Republican strategist who served as a senior adviser to Cuccinelli.

The Clinton family played a big role in helping build McAuliffe's political profile in Virginia. He initially ran for governor in 2009, despite spending very little time working with Virginia Democrats and after flirting with runs for governor in both Florida and New York.

Former President Clinton made several campaign appearances for his friend in the run-up to the 2009 primary, but McAuliffe lost a three way race to State Sen. Creigh Deeds. Deeds went on to lose to Republican Bob McDonnell in the general election.

In the years between his loss in 2009 and his second run in 2013, McAuliffe spent a lot of time with rank-and-file Virginia Democrats across the state.

He attempted to build his profile as a job creator by investing in a Chinese electric car company and purchasing an abandoned paper mill. The launch of the car company, "Greentech," in Mississippi was attended by former President Clinton. Hillary Clinton's brother, Tony Rodham, was part of a group that helped raise financial capital for the venture.

Shortly before he officially launched his second run for governor, McAuliffe sold his interest in Greentech and the company to this point has fallen well short of his lofty promise of potential jobs.

After McAuliffe eventually pulled out a victory, Bill and Hillary Clinton were standing right behind their friend -- arm-in-arm -- as the new governor was sworn into office.

Despite their history, McAuliffe rejected any attempt Tuesday to connect his predicament to Hillary Clinton.

"I don't think this has anything to do with Hillary Clinton," McAuliffe said.

The Clinton campaign declined to comment on the McAuliffe investigation.

Later on Tuesday, McAuliffe said he wasn't concerned about Republicans trying to link the investigation to Clinton.

"Let them do their attack. So what?" he said.

Asked if he has been in touch with the Clinton campaign, he said: "The thing I do every day to try and be the most helpful to Hillary Clinton is be a successful governor ... I'm governor now. I'm not her campaign chairman anymore, I am the governor of the commonwealth and that's what I spend my time doing."

But the ties between the McAuliffe campaign of 2013 and the Clinton campaign of 2016 are extensive. Clinton's campaign manager Robby Mook ran McAuliffe's successful campaign for governor. The attorney representing McAuliffe in this matter, Mark Elias, is also an attorney for the Clinton campaign. There are also several staffers on many levels working for Clinton that played key roles in the governor's 2013 race.

In addition to the specific personnel ties, the role of governor has traditionally been an important in the race for president in Virginia. In 2008, then-Gov. Tim Kaine was an early supporter of then-Sen. Barack Obama. He was eventually on Obama's short list for vice president and became an effective surrogate for Obama not only in Virginia but around the country. Kaine's work helped to deliver Virginia to Obama, the first time the state had awarded its electoral votes to a Democrat in a generation.

It was expected that McAuliffe -- who has already stumped for Clinton in Virginia -- would play a similar role in 2016.

Virginia Republicans, who are still smarting from the investigation and conviction of McDonnell, have been careful so far about attacking McAuliffe. But they can't resist pointing out how this issue could complicate life for Clinton.

"McAuliffe has raised and poured millions of dollars into the Democrat Party of Virginia in an effort to build the field structure that she's going to rely on," said RNC Virginia spokesman Garren Shipley. "I don't think it's a stretch to say that without Terry McAuliffe's money and organization, Hillary Clinton doesn't have much of a Virginia operation to speak of."

But even if the cloud of an investigation makes it too difficult for him to be an effective messenger for the Clinton campaign, there are other prominent Democrats who can pick up the slack. The party holds all five of Virginia's statewide elected positions -- among them Kaine, who is now a Senator and is once again rumored to be considered as a candidate for vice president. Sen. Mark Warner- a former governor himself- is very popular and also endorsed Clinton early on.

Meanwhile, McAuliffe argues there is nothing to be concerned about because he is confident that no one from his campaign has broken the law.

"If you haven't done anything wrong what should you be worried about?" he told reporters on Tuesday.