EDITOR’S NOTE: This story has been updated from its original version.

Authorities are operating under the working assumption there is a high chance Hillary Clinton’s private server was breached, one source with intimate knowledge of the FBI investigation told Fox News – though there still are no digital fingerprints proving a breach.

The source said the server may have been hacked by up to five foreign intelligence agencies. While other sources believe this is probable, evidence has not emerged to confirm this.

When FBI Director James Comey publicly discussed the Clinton email case back in July, he also said that while there was no evidence hostile actors breached the server, it was “possible” they had gained access.

On Thursday, House Homeland Security Committee Chairman Michael McCaul described Clinton’s handling of her email system during her tenure as secretary of state as “treason.”

“She exposed [information] to our enemies,” McCaul said on “Fox & Friends” Thursday morning. “Our adversaries have this very sensitive information. … In my opinion, quite frankly, it’s treason.”

Clinton herself has pushed back, saying the director in July was merely “speculating.”

The dispute comes as Comey’s FBI not only revisits the email investigation following the discovery of additional emails on the laptop of ex-Rep. Anthony Weiner – the estranged husband of Clinton aide Huma Abedin – but is proceeding in its investigation of the Clinton Foundation.

That investigation has now taken a “very high priority” among some local investigators on the ground, sources told Fox News.

There is a split, however, between local investigators and FBI headquarters, as well as with the Justice Department. 

Officials from the FBI did not immediately respond Wednesday to requests for comment by Fox News. 

Craig Minassian, with the Clinton Foundation, told Fox News in a statement: "We're not aware of any investigation into the Foundation by the Department of Justice, Federal Bureau of Investigation, or any United States Attorney's Office and we have not received a subpoena from any of those agencies.” 

The information follows a report over the weekend by The Wall Street Journal that four FBI field offices have been collecting information about the foundation.

The probes – in addition to the revived email investigation – have fueled renewed warnings from Republicans that if Clinton is elected next week, she could take office under a cloud of investigations.

“This is not just going to go away … if she ends up winning the election,” Rep. Ron DeSantis, R-Fla., told Fox News’ “America’s Newsroom” earlier this week.

Donald Trump has referenced this scenario, repeatedly saying on the stump this past week that her election could trigger a "crisis.”

“It would create an unprecedented and protracted constitutional crisis,” Trump said Wednesday in Miami.

Fox News first reported in January that the FBI investigation into Clinton’s use of private email as secretary of state had expanded to look at whether the possible “intersection” of Clinton Foundation work and State Department business may have violated public corruption laws.

Clinton told The Des Moines Register at the time that the claim was “without merit” and she had heard nothing from the FBI.

Fox News’ Bret Baier and Mike Emanuel contributed to this report.