DEBBIE WASSERMAN SCHULTZ UPDATE: IT staffers may have compromised sensitive data to foreign intelligence.

Federal authorities are investigating whether sensitive data was stolen from congressional offices by several Pakistani-American tech staffers and sold to Pakistani or Russian intelligence, knowledgeable sources say.

What started out 16 months ago as a scandal involving the alleged theft of computer equipment from Congress has turned into a national-security investigation involving FBI surveillance of the suspects.

Investigators now suspect that sensitive US government data — possibly including classified information — could have been compromised and may have been sold to hostile foreign governments that could use it to blackmail members of Congress or even put their lives at risk.

“This is a massive, massive scandal,” a senior US official familiar with the widening probe told The Post.

Flashback: Politico: Blowback from staffer scandal burns Wasserman Schultz.

One year after the Florida congresswoman’s resignation as national party chair at the Democratic National Convention — where activists booed and shouted “shame!” at her during a Florida delegation breakfast speech — the once-rising star’s political fortunes continue to fade, beset by critics on all sides.

Wasserman Schultz is again on defense after steadfastly refusing to explain why she continued to employ Imran Awan, an IT staffer who was under a federal investigation for alleged equipment and data scam in the U.S. House since February. She finally fired him on July 25, one day after authorities arrested him on a seemingly unrelated mortgage fraud charge. He was at the airport leaving for Pakistan, after wiring $283,000 there.

The firing came a full six months after about two dozen House Democrats dismissed four of Awan’s relatives and a friend, all of whom were under investigation with him.

Wasserman Schultz broke her public silence on Awan last week, portraying herself as the victim of “right wing media” attacks rooted in anti-Muslim bigotry aimed at Awan and the IT group.

But fellow Democrats are as confounded and disbelieving as ever by her penchant for making puzzling and stubborn political missteps.

“We wish she would go away and stop being so public by doubling down on negative stories,” said Nikki Barnes, a progressive DNC member from Florida, who believes Wasserman Schultz left the national party “in shambles” while chair, culminating with the hack of DNC servers and the release of embarrassing internal emails by WikiLeaks in the 2016 campaign. As for Wasserman Schultz’s defense, Barnes said “none of this makes sense. It doesn’t sound like racial profiling … there must have been something for her.” . . .

Barnes said she couldn’t understand why Wasserman Schultz made herself a target of attention by becoming the lone Democrat to employ Awan. Wasserman Schultz then drew even more negative attention to herself by publicly threatening the Capitol Police chief with “consequences” in a dispute over an office laptop under examination from investigators.

Indeed.

Flashback: House IT Aides Fear Suspects In Hill Breach Are Blackmailing Members With Their Own Data.