“The impression this leaves is that Trump isn’t interested in science and that scientific matters are a low priority at the White House,” said Vinton G. Cerf, a computer scientist, vice president of Google and one of the chief architects of the internet. The dwindling of the White House science and technology staff for scientific research could have long-term consequences, Mr. Cerf said.
It is unclear whether the vacancies are the result of the Trump administration’s overall slowness in hiring or a signal that the president places less importance on science and technology than Mr. Obama did.
A White House official who asked not to be identified cast the issue as one of timing: Mr. Trump, the official said, is still reviewing candidates to be his chief science adviser, considers the science and technology office important and will soon have a new staff for it.
But critics see the empty offices as part of a devaluation of science throughout the Trump administration, including the reversal of Mr. Obama’s climate change policies and proposals to sharply reduce spending for research on climate change, science and health. They note that Mr. Obama appointed his top science adviser, John P. Holdren, a Harvard physicist and climate-change expert, in December 2008, weeks before his inauguration.
At the same time, conservatives — including a member of Mr. Trump’s transition team — have called for getting rid of the White House Office of Science and Technology Policy. (The chief technology officer is a part of that larger office.) They argue that the office, created by Congress in 1976, is a bloated bureaucracy that duplicates expertise already found at government agencies.
“Eliminating the O.S.T.P. (or at least electing not to staff it until Congress can act) would not block the president from access to science and technology advice,” James Jay Carafano, who advised Mr. Trump’s transition team, wrote in a report issued last summer by the conservative Heritage Foundation. “Rather, it eliminates a formal office whose purpose is unclear and whose capabilities are largely redundant.”
Mr. Trump has echoed that sentiment, at least when it comes to government jobs over all.
Last month he responded to criticism about the high number of vacancies across his administration by telling Fox News that “a lot of those jobs, I don’t want to appoint, because they’re unnecessary to have.”
“You know, we have so many people in government, even me,” Mr. Trump said. “I look at some of the jobs and it’s people over people over people. I say, ‘What do all these people do?’ You don’t need all those jobs.”
If Mr. Trump applies that logic to the science and technology office, he will end decades of tradition in which the president increasingly relied on his own advisers for expertise on federal research budgets, emerging trends and technical crises.
Mr. Trump’s first budget proposes slashing $5.8 billion, or 18 percent, from the National Institutes of Health and $900 million, or about 20 percent, from the Energy Department’s Office of Science, which runs basic research at the national laboratories. The Environmental Protection Agency would be cut by 31 percent.
On Tuesday, Mr. Trump issued executive orders that roll back Mr. Obama’s Clean Power Plan, which would have closed hundreds of coal-fired power plants in an effort to curb planet-warming carbon dioxide emissions.
Those actions have been taken without advice or guidance from scientists and engineers inside the White House. The few remaining policy advisers have ceased distributing daily memos on policy issues like climate change, machine-learning regulation, or the ethics of big data collection.
“They are flying blind when it comes to science and tech issues,” said Kumar Garg, who left the Office of Science and Technology Policy as a senior adviser after the election.
There is no question that the science and technology bureaucracy at the White House expanded in recent years. In the George W. Bush administration, there were 50 people in the office, but Mr. Obama more than doubled the staff, to 130, and moved the office into a building on the White House grounds.
Mr. Obama turned to the science office during crises like the 2014 Ebola outbreak in Africa; the 2011 nuclear spill in Fukushima, Japan; and the Deepwater Horizon oil spill in the Gulf of Mexico in 2010.
The staff of the science office developed the White House’s recommendations for regulation of commercial drones and driverless cars at the Transportation Department. Last year, the staff produced an attention-grabbing report that raised concerns about the threat that robots posed to employment and that advocated retraining Americans for higher-skilled jobs. The staff also put on the annual White House science fair.
In 2011, when lawmakers proposed an online piracy bill known as the Stop Online Piracy Act, internet architecture engineers on the team advised the president to veto the bill because of security and privacy issues it would create.
“The agenda was always huge in scope and ambition, and something was always happening,” said Nicole Wong, a former deputy chief technology officer under Mr. Obama.
The departure of science and technology experts from the White House means dozens of science and technology programs begun during Mr. Obama’s term have gone untended in the weeks since Inauguration Day.
“The O.S.T.P. is the conduit for scientific perspective and scrutiny to the president and is a priority in White House decision making,” said Danny Weitzner, a former deputy chief technology officer in the Obama administration and now the director of internet policy research at M.I.T.
Under Mr. Obama, the science and technology office included 19 policy advisers in the environment and energy division, 14 in the national security and international affairs division, nine in the science division and 20 in the technology and innovation division.
“We are all sitting on the edge of our seats hoping nothing catastrophic happens in the world,” said Phil Larson, a former senior science and technology adviser to Mr. Obama. “But if it does, who is going to be advising him?”
Current White House officials declined to say how many people remained in each division. But four former officials who recently left the office said that a wave of departures scheduled for Friday could potentially reduce the number of people left to a handful, not counting about eight administrative staff members.