Donald Trump has denied the use of a government aircraft to House of Representatives Speaker Nancy Pelosi in an apparent response to her attempt to delay his State of Union address amid their government shutdown clash.
The nation's two most powerful leaders appeared to be engaged in a game of Constitutional one-upmanship, as negotiations to end the four-week stalemate failed to produce results.
In a letter to Ms Pelosi on Thursday, Mr Trump said that, due to the shutdown, a trip to Egypt, Brussels and Afghanistan would be delayed, declaring: "In light of the 800,000 great American workers not receiving pay, I'm sure you would agree that postponing this public relations event is totally appropriate."
While the shutdown dragged on, the US State Department instructed all US diplomats in Washington and elsewhere to return to work next week with pay, saying it had found money for their salaries at least temporarily despite the ongoing government shutdown.
In a notice to staff posted online and sent to employees, the department said it had found money to pay most of its employees beginning Sunday or Monday for their next pay period.
They will not be paid for time worked since the shutdown began in December until the situation is resolved, said the notice, which was signed by William Todd, the deputy undersecretary of state for management.
It was not immediately clear where the money was found, but the department said it would use "existing funds as well as other available fiscal authorities to shift existing balances to restart payroll funding".
Salaries cannot be guaranteed beyond the next pay period, which ends on February 14, if the shutdown does not end by then, the department said.
However, it said it would "review its balances and available legal authorities to see if other flexibilities may be available".
The department said it was taking the step because it had become clear that the lapse in funding is harming essential diplomatic and national security objectives.
“While the department has done its best to address matters essential to achieving US national security and foreign policy objectives during the ongoing lapse, it has become clear as the lapse has continued to historic lengths that we need our full team to address the myriad critical issues requiring US leadership around the globe and to fulfil our commitments to the American people,” it said.
It added that the department’s leadership was “deeply concerned” about the financial hardships faced by its employees.
Secretary of State Mike Pompeo had raised eyebrows among the US diplomatic corps last week when he proclaimed that morale at the State Department was "good" despite the shutdown and the fact that 40% of its employees in the US and nearly 23% overseas had been rested and the rest were working without pay.
His comments also touched a nerve as he said he planned to go ahead with a previously scheduled conference of all US ambassadors in Washington this week despite the funding constraints affecting employees.
Deputy Secretary of State John Sullivan announced the return to work with pay instructions to that conference on Thursday and was greeted with two rounds of sustained applause, according to one diplomat who was present.
The shutdown, already the longest ever, entered its 27th day on Thursday.
While Mr Trump's own advisers said the shutdown was proving a greater drag on the economy than expected, Mr Trump showed no signs of backing off a fight that he views as vital for his core supporters.