But the lull did not last long.

Mr. Trump’s decision to revoke Ms. Pelosi’s military transport drew howls of outrage from Democrats and some Republicans, and threw into disarray a long-planned trip by the speaker and senior lawmakers — including the chairmen of the House Intelligence and Foreign Affairs Committees — to visit American allies and troops stationed overseas.

Democrats, newly in control of the House and eager to use their power to challenge Mr. Trump, vowed that they would not be bullied into scrapping the trip altogether.

Image The dueling letters: Speaker Nancy Pelosi sent a letter to President Trump on Wednesday about the State of the Union address.

“We’re not going to allow the president of the United States to tell the Congress it can’t fulfill its oversight responsibilities, it can’t ensure that our troops have what they need whether our government is open or closed,” said Representative Adam B. Schiff of California, the chairman of the intelligence panel.

“We are a coequal branch of government,” Mr. Schiff said, suggesting that the president apparently did not understand the new reality in Washington. “It may not have been that way with the past two years when he had a Republican Congress willing to roll over anytime he asked, but that is no longer the case.”

Mr. Schiff was on the bus outside the Rayburn House Office Building near the Capitol when Mr. Trump fired off his letter, along with Representative Eliot L. Engel, Democrat of New York and the chairman of the Foreign Affairs Committee, and several other lawmakers in what made for an unusual tableau.

Instead of heading for Joint Base Andrews and boarding a military plane, the lawmakers sat stunned on their bus, unsure of what to do next, until it eventually drove slowly to the Capitol driveway — some journalists jogging or riding electric scooters to keep up — to disgorge its perplexed passengers. At one point, the House sergeant-at-arms, the chamber’s chief law enforcement officer, turned up to puzzle over the security arrangements for the lawmakers, whose secret travel plans were now public. And the speaker, holed up in her office with aides as reporters mixed near the Rotunda with tourists oblivious to the drama, calmly plotted her next steps.