President Donald Trump and Secretary of State Marco Rubio are weighing the dismissal of U.S. Ambassador to Greece Kimberly Guilfoyle following a string of reports alleging that she engaged in improper and potentially illegal conduct before and during her tenure in Athens. U.S. ambassadors are nominated by the president, confirmed by the Senate, and serve at the pleasure of the president, who can recall them at any time. The post carries responsibility for U.S. diplomatic relations with Greece, a NATO member since 1952.

A senior U.S. official said Sunday that Trump and Rubio are "extremely pissed off" by Guilfoyle's reported conduct and would likely decide this week what action to take, after Monday's Columbus Day holiday. The official, who spoke on condition of anonymity to discuss internal deliberations, said Rubio had grown particularly angry — not least because he visited just last week, where Guilfoyle attended most, if not all, of his events and greeted him on arrival with a bear hug even as the allegations swirled.

The Wall Street Journal has published a series of stories describing questionable conduct by Guilfoyle, including an alleged threat against a host-country official, the acceptance of improper gifts and services, and an offer to use her influence within the administration in exchange for the payment of a large credit card bill. Federal ethics rules restrict the gifts and outside benefits that executive branch employees may solicit or accept.

Guilfoyle has not directly addressed the reports, but her lawyer has said she did nothing wrong, and the U.S. embassy in Athens has tacitly expressed support for her.

Rubio defended Guilfoyle after the first report but has since declined to comment publicly as the allegations mounted. On Wednesday, he said: "Our ambassador has been a strong ambassador here." After another report appeared late Wednesday, however, Rubio berated journalists on Thursday before departing Athens, saying he did not know whether the allegations were true and would not respond if he could not confirm them.

"You guys walk around thinking that because some source told you something and you reported it, it's the gospel. It's not the gospel. It's not the gospel for me. That's not the way we do things," Rubio said at the foot of his plane, as Guilfoyle, who was there to see him depart, looked on.

The senior official said Rubio had grown increasingly frustrated as the reports multiplied.

A second U.S. official, also speaking on condition of anonymity to discuss personnel matters, said the State Department's inspector general is looking into the allegations, which first began surfacing in the Journal late last month and have since multiplied. The second official could not say whether a formal IG probe had begun. Inspectors general often conduct informal inquiries into complaints against staffers, and many such inquiries do not lead to a full investigation, which can result in disciplinary action up to and including dismissal. The State Department has declined to comment on a potential IG investigation.

The top Democrats on the House Foreign Affairs and Senate Foreign Relations committees — Rep. Gregory Meeks of New York and Sen. Jeanne Shaheen of New Hampshire — as well as the ranking member of the House Committee for Oversight and Government Reform, Rep. Robert Garcia, D-Calif., have already called for an investigation into Guilfoyle.

Since late September, the Journal has detailed numerous accounts of questionable conduct by Guilfoyle. Its first report said she had told guests at a reception that the United States could undermine the Greek government if it chose to, promoted the business interests of one particular Greek construction and energy company, and allowed the company's lobbyist into private diplomatic meetings.

While Rubio was in Athens, the Journal reported — citing text messages — that Guilfoyle had asked a Trump donor and supporter to pay a $100,000 credit card bill shortly before her confirmation hearing, promising him access to administration officials in return.

The Journal subsequently reported that Guilfoyle had been enraged at not being invited to a Greek-themed event at the World Economic Forum in Davos, Switzerland, earlier this year, demanded to attend, and boasted about luxury travel to France with energy company executives.

A separate report from the British tabloid The Daily Mail said Guilfoyle had alienated staff at the U.S. embassy in Athens and had pushed the bounds of behavior appropriate for the top U.S. government representative to Greece.

Guilfoyle is a former Fox News Channel host and California prosecutor who was once engaged to Trump's son, Donald Trump Jr.

This story was originally featured on Fortune.