1. A few members of Congress were on a bus, heading to Andrews Air Force Base for their first leg of an unannounced trip to Afghanistan, when President Trump sent a letter addressed to House Speaker Nancy Pelosi.

“I am sorry to inform you that your trip to Brussels, Egypt and Afghanistan has been postponed,” Mr. Trump wrote. “We will reschedule this seven-day excursion when the shutdown is over.”

The point was clear. A day earlier, Ms. Pelosi said Mr. Trump’s State of the Union address should be delayed — or delivered only in writing — because of security concerns raised by the government shutdown. She has continued to push her case for a delay, and also hinted that Democrats would begin promoting their own proposals for border security.