The White House began courting Republican members of Congress, holding a round of lunches at the White House, taking lawmakers on Air Force One and opening up Camp David for weekend getaways. Mr. Trump met with over 120 House Republicans and nearly all 53 Senate Republicans.

Republicans also focused their fire on how Democrats were proceeding with the impeachment inquiry, recasting the investigation as a familiar partisan conflict.

Rep. Francis Rooney, a moderate Republican from Florida, announced his plan to retire in October, one day after criticizing the White House for its interactions with Ukraine. But he stuck with the president on the House’s impeachment votes, and he said the speed with which Democrats pursued the inquiry rubbed him the wrong way.

“They were conducting more of a political process and they wanted to get it out of the way,” Mr. Rooney said. “There were several people like me who thought it was disturbing but didn’t rise to the level of impeachment.”