That might seem like business as usual for Americans who accepted candidate Trump’s description of Washington as rife with influence peddlers and profiteers. But it might actually be worse than usual. Because of the extraordinarily high rate of turnover that is a hallmark of the Trump administration, the White House’s human resources professionals have had little time to come up with outside-the-Beltway replacements for the constant stream of openings, Mr. LaPira said.

Jordan Libowitz, a spokesman for Citizens for Responsibility and Ethics in Washington, a liberal watchdog group, called the proliferation of lobbyists in Mr. Trump’s cabinet deeply worrisome. He pointed to David Bernhardt, a former oil and gas lobbyist who served as deputy secretary of the Interior Department before he replaced Mr. Zinke in April as Interior secretary.

Mr. Bernhardt has been dogged by ethics investigations since he joined the Trump administration, in large part because of his lobbyist past. In April the Interior Department’s internal watchdog opened an inquiry into allegations, revealed by New York Times investigations, that Mr. Bernhardt used his position to advance a policy pushed by his former lobbying client.

“The revolving door between industries and lobbying in the administration has always been a thing, but it is much more pronounced right now,” Mr. Libowitz said. “It raises the question of whether things are being tilted in favor of industry as a rule, over what may be in the interest of the American people.”

Elevating officials working as deputies or in the agency’s trenches is nothing new. But Mr. Trump’s penchant for simply promoting No. 2 officials to cabinet posts appears to be more a matter of expediency than a reward for hard work. Deputy secretaries have already been through grueling Senate confirmations, thus mostly eliminating the element of surprise in an administration not known for employing a stringent vetting process.

And for a president who has openly expressed his preference for having “acting” secretaries instead of confirmed ones, elevating a No. 2 to “acting secretary” avoids running afoul of a longstanding law, the Vacancies Act, that requires secretary positions to go to ranked officials in the department who have been confirmed by the Senate.

“The desirability of working for this president and working in these high profile jobs gets riskier and riskier over time, so I suspect the pool of applicants has also declined,” said Kathryn Dunn Tenpas, a nonresident senior fellow at the Brookings Institution. Elevating a No. 2, she added, is “the path of least resistance.”