An end to the government shutdown looked more distant than ever on Thursday after President Donald Trump abruptly canceled Speaker Nancy Pelosi’s planned visit to Afghanistan.

The White House publicly released a terse letter informing Pelosi that her planned travel had been “postponed,” shortly after Trump ordered the Pentagon to cancel her Air Force flight to the country. A bus carrying several House Democrats who were to accompany Pelosi was preparing to leave for the airport at the time.

The extraordinary affront appeared to be payback for Pelosi’s request that Trump postpone his annual State of the Union address, scheduled for Jan. 29, though White House officials insisted it wasn’t a tit-for-tat. Pelosi, in her Wednesday letter to Trump, suggested that the partial government shutdown, soon to enter its second month, would create security concerns — a claim the Trump administration contested.

The dueling moves further personalized the shutdown standoff, which centers on Trump’s demand for $5.7 billion to fund a barrier along the U.S.-Mexico border, and suggested that a Trump-Pelosi relationship that has stayed more or less cordial might be plunging into open hostility.

That could make it even more difficult for the president and his House Democratic rival to strike some kind of face-saving bargain that would resume paychecks for 800,000 federal employees — and many more contract workers — who have not been paid in weeks.

“Due to the Shutdown, I am sorry to inform you that your trip to Brussels, Egypt, and Afghanistan has been postponed,” Trump wrote in his letter to Pelosi. “We will reschedule this seven-day excursion when the Shutdown is over. In light of the 800,000 great American workers not receiving pay, I am sure you would agree that postponing this public relations event is totally appropriate.” Pelosi’s delegation was actually scheduled to return Tuesday, after only six days of travel.

In his letter, the president called on Pelosi to remain in Washington during the shutdown, adding that lawmakers are welcome to travel abroad on commercial flights.

Despite Trump’s decision to cancel the congressional trip, First Lady Melania Trump appeared to be traveling to Palm Beach, Florida, on a military plane soon after the president released the letter, according to amateur flight trackers. The first lady’s spokeswoman did not respond to requests for comment.

Democrats said they were blindsided by the letter, which the White House sent to reporters and which White House press secretary Sarah Huckabee Sanders posted on Twitter.

Budget negotiations between the White House and Democratic leaders have virtually ceased and there are no signs of a compromise on the horizon. The 27-day partial shutdown, which has closed nine of 15 federal departments, is now the longest in U.S. history.

On Thursday, Vice President Mike Pence and Jared Kushner, Trump’s son-in-law and senior adviser, traveled to Capitol Hill to meet with Senate Majority Leader Mitch McConnell.

The president has generally avoided direct attacks on Pelosi, whom aides said he begrudgingly respects. But Thursday’s letter signaled that Trump will no longer soften his tone toward the House speaker.

White House officials insisted that the letter was not a response to Pelosi’s call to cancel the State of the Union but rather an effort to ensure that talks to end the shutdown are not delayed. Trump aides said there were no plans to postpone the State of the Union speech at this time.

“She wasn’t scheduled to be back until Wednesday. The president wants her here to negotiate,” Sanders told reporters, although Pelosi was scheduled to get back on Tuesday. Sanders added that federal workers are guaranteed to miss another paycheck if the shutdown isn’t over by midway through next week.

The White House blasted out its letter to Pelosi shortly after 2 p.m — about an hour before Pelosi and other Democrats planned to depart for the six-day trip, according to a person familiar with the situation. Reporters were the first to inform lawmakers about the missive.

The scene around the Capitol quickly devolved into a circus-like atmosphere as reporters chased a charter bus with lawmakers on board who were supposed to join Pelosi on the trip overseas.

A crew of cameras and reporters, many without coats in the frigid temperatures, joined in on the impromptu stakeout as the bus idled outside a House office building before driving onto the Capitol grounds only to depart again to do a lap past the Senate offices and the Supreme Court.

The chaotic scene played out more than 24 hours after Pelosi sent her own letter to Trump, requesting he postpone the State of the Union. Senior aides had initially made a strategic decision to hold off on responding, according to people familiar with the matter.