WASHINGTON — A fourth employee has left the Department of Labor after being sidelined amid a sprawling watchdog probe of Secretary Lori Chavez-DeRemer involving alleged travel fraud and other misconduct, The Post has learned.

Melissa Robey, who served as director of advance in the secretary’s office, was fired on Tuesday at the prompting of the White House, sources said.

On March 4, Robey was put on administrative leave following allegations that she misused taxpayer dollars for official travel — one day after Chavez-DeRemer’s two top aides resigned from their positions while facing similar allegations.

Investigators had gathered evidence of a “toxic” workplace created by chief of staff Jihun Han and his deputy Rebecca Wright, including verbal abuse of staffers and waste of departmental resources on personal trips, sources noted.

The senior aides were also accused of committing “travel fraud” by helping “make up” official trips to destinations where Chavez-DeRemer, 57, could spend personal time on the taxpayers’ dime.

People familiar with the probe added that Robey, who acknowledged that she had been interviewed by investigators on Monday, also had excessive travel-related expenditures.

In a statement Thursday, Robey said she was wrongfully terminated “with no explanation” and claimed that “cowardly” DOL staff sought “to embarrass and defame me in a failed effort to force me to resign.”

“The pettiness has included questioning me why the Secretary [Chavez-DeRemer] traveled in a Ford Expedition and not a foreign-made, sub-compact car on a 470-mile winter drive through North Dakota. I believe any cabinet official of the United States of America should travel in a safe American-made car,” she added.

“I did nothing wrong and have nothing to hide.”

In addition to Han, Robey and Wright, Brian Sloan — a bodyguard on Chavez-DeRemer’s security detail — was sidelined on Jan. 16 following allegations of having an extramarital affair with the secretary. He resigned earlier this month.

Neither Han, Wright nor Sloan were interviewed before departing DOL, per sources.

Since January, DOL Inspector General Anthony D’Esposito’s office has been probing allegations of misconduct — first exposed by The Post — that also claimed Chavez-DeRemer was abusing her position and even drinking in her office during the workday.

Senate Judiciary Committee Chairman Chuck Grassley (R-Iowa) has also demanded information about the alleged sexual and workplace misconduct — including evidence that the secretary took subordinates to an Oregon strip club shortly after she was confirmed by the Senate in April 2025.

The White House has stood by Chavez-DeRemer throughout the investigation, with President Trump frequently praising her work at DOL during public events.

Han and Wright had worked for Chavez-DeRemer in the House of Representatives, where she represented Oregon’s 5th Congressional District from 2023 to 2025.

The Treasury Department had to pay out nearly $100,000 in taxpayer-appropriated money last year to settle an employment discrimination claim stemming from Chavez-DeRemer’s congressional office — the highest sum recorded since 2019.

“It is the policy of the Department of Labor not to comment on personnel matters,” a DOL spokesperson said.

The White House did not respond to a request for comment.