“What makes this a unique opportunity in modern history is the sheer number of vacancies, the number of potential vacancies because of the aging bench, and the existence of a president who really cares about this issue in his gut,” said Leonard A. Leo, an informal adviser to Mr. Trump on courts who is the executive vice president of the Federalist Society.

Liberals have accused Mr. Trump of outsourcing his nominations process to the Federalist Society. But two administration officials argued that this claim misunderstands how the conservative legal movement has matured as the generation of Republican lawyers shaped by reading the originalist dissents of Justice Scalia and by the bitter 1987 fight over Judge Robert H. Bork’s failed Supreme Court nomination has come of age. Mr. McGahn and nearly all the lawyers working for him at the White House are longtime society participants, so relationships built on the network of like-minded conservatives saturate discussions of potential nominees from the inside, they said.

Mr. Trump has also had help from the Senate Judiciary Committee chairman, Charles E. Grassley, Republican of Iowa, in lowering impediments and keeping the confirmation assembly line moving.

For example, confirmation hearings have usually featured just one appellate hopeful at a time (along with several district judge nominees). But Mr. Grassley has scheduled three hearings this year with two appellate nominees — as many as took place during all eight years of the Obama administration, according to congressional aides.

The independent guardrail role of the American Bar Association, which has vetted potential judges since the Eisenhower administration — conducting confidential interviews with people who worked with them and rating their experience, integrity and temperament — is also weakening. Picks by presidents of both parties have sometimes run into trouble, but Republicans have accused the group of bias against conservatives.

Traditionally, the group’s volunteers vet potential judges before the White House decides whether to send their names to the Senate, but Mr. Trump — like President George W. Bush — exiled it from that role, leaving it scrambling to evaluate nominees afterward. Already this year, Mr. Grassley has held hearings for four district judge nominees before the group finished its work — which happened with only seven during the eight Bush years.