Republican lawmakers appear more than ready to open up the coffers for a $12 billion to $15 billion border wall, perhaps without the commensurate spending cuts that they demanded when it came to disaster aid, money to fight the Zika virus or funds for the tainted water system in Flint, Mich. They also seem to back a swelling of the federal payroll that Mr. Trump has called for in the form of a larger military and 5,000 more border patrol agents.

They have stayed oddly silent as Mr. Trump and Senate Democrats push a $1 trillion infrastructure plan, larger than one they rejected from President Barack Obama. Once fierce promoters of the separation of powers, Republicans are now embracing Mr. Trump’s early governing by executive order, something they loudly decried during Mr. Obama’s second term.

Speaker Paul D. Ryan, whose own website this week still praised the Trans-Pacific Partnership trade deal, now applauds Mr. Trump for putting the final shovel of dirt over the accord, with the president saying he is interested in bilateral agreements instead.