Mr. Trump’s choice, Representative John Ratcliffe of Texas, has established himself during his nearly five years in Congress as a tough partisan and as one of Mr. Trump’s most effective defenders. A relentless critic of the Russia investigation, Mr. Ratcliffe has shared some of Mr. Trump’s views and earned praise from critics of the so-called deep state of government bureaucrats.

Democrats have said he is unqualified and too overtly political, and even some Republicans privately said they thought Mr. Ratcliffe was the wrong choice, according to people familiar with their thinking. Senator Richard M. Burr, Republican of North Carolina and the Senate Intelligence Committee chairman, waited nearly a day to publicly congratulate Mr. Ratcliffe, a subtle sign of discontent with the shake-up. But Republicans on the committee, which will vote on whether to send the nomination to the full Senate, are highly unlikely to buck Mr. Trump.

The political winds from the Trump White House have buffeted the intelligence agencies, and Dan Coats, the current director of national intelligence, has worked to insulate them. If Mr. Ratcliffe is confirmed for the post, some current and former American officials believe that other top intelligence officials like the C.I.A. director, Gina Haspel, and the F.B.I. director, Christopher A. Wray, could lose their shield against White House interference and partisan criticism.