Senator Thom Tillis, Republican of North Carolina, distinguished himself with the most adorable distraction: He cradled a Boston terrier puppy, stroking her chin, as he greeted reporters eager to ask about Mr. Trump this week in the basement of the Capitol.

“Her name is Tilly,” he said, before politely shrugging off questions about Mr. Trump.

The first several days of the Trump presidency have reinforced several core truths: He will continue to give voice to conspiracy theories and peddle misinformation. He will not stop obsessing over cosmetic displays of popularity, like crowd size and television ratings.

And if Republican lawmakers harbored any expectation that this ritual of the campaign cycle would end — the grimacing through questions about Mr. Trump, the hedging when asked if their party’s leader had overstepped — these early days have supplied a decisive verdict: not so much.

On Thursday, Republicans welcomed Mr. Trump to their party retreat here — the headliner of an outing that also includes Prime Minister Theresa May of Britain and Peyton Manning, the retired football star.

The event is fashioned as an off-site exercise in legislative sausage-making, with Republican members of both congressional chambers talking agenda by day and indulging in occasional cocktails by nightfall. At one of the gathering’s early sessions on Wednesday, Mr. Ryan outlined the party’s aggressive plan for Mr. Trump’s first 200 days, including repealing and replacing the Affordable Care Act over the next few months, coming up with money for a border wall and working to complete tax reform by the August recess.