Some of President Trump's staunchest allies have lost confidence in the administration's ability to fill several high-level vacancies that remain within the government, already casting doubt on whether the White House will decide on replacements for Tom Price at Health and Human Services and John Kelly at the Department of Homeland Security by the end of the year.

Price resigned last month after his penchant for taxpayer-funded private planes over commercial flights was revealed in a series of reports. Last week, the Senate confirmed Eric Hargan, a former HHS appointee under President Bush, to be deputy secretary of the agency in a 57-38 vote.

Hargan will serve at the helm of the agency while White House officials search for a permanent successor to Price.

The former Georgia congressman's resignation came months after Kelly left DHS to join the West Wing as Trump's chief of staff. A source close to the agency said it is unlikely the White House will permanently elevate acting DHS secretary Elaine Duke to the position, despite the praise Trump has heaped on her after the recent hurricanes.

Administration officials are "nowhere closer to finding a replacement than they were last month or [in] August," the source said. Kelly stepped down from his senior law enforcement position on July 28, giving the administration five months to settle on his replacement before Trump approaches the end of his first year.

A former White House aide said Trump is largely to blame for the delay because he "wants someone along the lines of David Clarke" to occupy the position. Clarke, the controversial ex-sheriff of Milwaukee County, Wis., recently took a job at the pro-Trump outside group America First Action.

Supporters of the president, who said it could take months for the White House to decide on nominees for HHS and DHS, pointed to myriad other positions that remain vacant or were just recently filled nearly nine months into Trump's first term.

In early August, for example, at least eight Cabinet agencies lacked deputy secretaries, including HHS, Energy, Housing and Urban Development, Office of Management and Budget, Education, Labor, Veterans Affairs and Agriculture. The Senate has since confirmed deputy Agriculture secretary Stephen Censky, deputy HUD secretary Pamela Hughes Patenaude, deputy Energy secretary Dan Brouillette, and deputy VA secretary Thomas Bowman.

Nominees for Labor and OMB are still awaiting a final confirmation vote, while the White House just nominated a deputy education secretary last Wednesday.

A former Trump transition official, who worked to vet possible Cabinet and administration appointees in the months before the inauguration, described the slow pace as "baffling."

"We spent months – went through literally thousands and thousands of résumés — and then, come Jan. 20, it was as if we hadn't done any work," the official, who went on to serve in the White House, told the Washington Examiner. "There has been some kind of significant disconnect between the work we did on transition and the staffing on the ground."

Since taking office, Trump has sent 362 non-judicial nominees to the Senate for confirmation out of 1,212 administration positions that require approval by the upper chamber, according to a tracker by the independent Partnership for Public Service. Slightly more than 150 nominees have been confirmed, after spending an average of 59 days in limbo while Senate committees conducted hearings and recommended them for final votes.

By comparison, former President Barack Obama had installed 334 senior administration officials by October of his first year in office, President George W. Bush 355, and President Bill Clinton 283. Trump's three immediate predecessors each sent more than 400 nominees to the Senate by the end of September their first year as president.

"There really is no excuse, in many cases, for the lack of positions being filled," the ex-transition official said.

Not only can the absence of political appointees hinder daily operations across the government, the administration's lack of allies in influential positions can also slow implementation of the policies Trump hopes to enact.

"He should put renewed effort into turning the lights on in management offices all over town, simply out of interest in advancing his own agenda," wrote the Washington Post editorial board in late August.

Still, Trump has struggled to advance key agenda items even with conservative allies installed throughout his Cabinet — something that is likely to be considered as the president and his team continue their searching for replacements at DHS and HHS.

In the weeks leading up to Price's resignation, the president was said to have become frustrated with his HHS secretary's level of involvement in several Obamacare repeal efforts that eventually failed in the Senate.