By Rene Marsh, CNN

(CNN) -- A key staff change at the Department of Housing and Urban Development is again shining a spotlight on what some HUD insiders and former senior staff say is a notable lack of government, policy and relevant experience in some key positions at the agency.

Andrew Hughes, 32, is now serving in a powerful senior level position as chief of staff to HUD Secretary Ben Carson. As Hughes experiences a meteoric rise, the department's deputy chief of staff, Deana Bass, will leave the department in early June, two sources familiar with the changes tell CNN.

Bass' departure leaves Carson without one of the first aides he hired as a newcomer to politics, with Bass having previously served as the press secretary for his 2016 presidential campaign. Hughes and Bass served jointly in the deputy chief of staff role, and Hughes was promoted as the department plans for Bass' departure.

CNN's review of Hughes' prior experience and employment as listed on his financial disclosure form found that, just eight months before joining HUD, Hughes worked as a special projects coordinator for the University of Texas System and briefly as an Uber driver.

During his time at the university, Hughes managed social media and websites, compiled press releases, planned university events, researched funding opportunities and kept abreast of any legislation related to higher education, according to his resume, obtained through a freedom of information request by American Oversight, a watchdog group with former Obama appointees.

Hughes began at HUD as the department liaison to the Trump White House in January 2017. Prior to that, Hughes worked on Carson's presidential effort as part of the campaign's get out the vote effort and then served in a similar capacity for three months with Donald Trump's campaign.

Former political appointees from both parties, along with current department staff, have expressed concern that Carson, a medical doctor with no government experience prior to taking the reins of HUD, is surrounded by some advisers and now a chief of staff who are similarly inexperienced.

Asked about Hughes's resume, HUD spokesman Raffi Williams said Carson has "the upmost confidence" in his staff.

Pamela Patenaude currently serves as the deputy secretary, and by many accounts, she is leading the day-to-day operation. Patenaude previously worked on housing in the non-profit world and as an assistant secretary at HUD. There are also some assistant secretaries currently working at the agency with prior HUD experience.

Criticism of Carson's staff selection is coming from both sides of the aisle.

"There are some on staff with prior experience and some who have served at the agency before and they're holding down the fort, but they can't do it on their own, they need experienced people around them," a former Bush appointee at HUD, who asked for anonymity to freely speak about the agency now run by a fellow Republican, told CNN.

"The quality of appointees in leadership is lacking. The agency is not being set up for success when comes to challenges facing HUD. Some of the appointees are not experts in the field, the former Bush appointee added.

"I don't have a sense Carson has surrounded himself with enough knowledgeable people from discussions I've had with career staff and some of the political staff," said a former HUD senior adviser on rental assistance during the Obama administration who asked for anonymity because they currently work for a non-partisan organization working on HUD-related issues.

Another current HUD employee highlighted the significance of the chief of staff role at HUD.

"At HUD the chief of staff position is a very senior, very powerful position," the source said, noting that the chief of staff has the power to reassign staff and adding that "when you look at any documentation concerning policy or official acts of the agency that's cleared by the Secretary, it's usually cleared through the chief of staff first."

CNN spoke to Hughes' colleagues, Todd Richardson, acting assistant secretary for policy development and research, and Jereon Brown, general deputy assistant secretary for public affairs about Hughes' recent promotion to chief of staff.

"The experience would be beneficial, but the chief of staff that's most effective is the one that knows what questions to ask," Brown said.

"He is a very even tempered and thoughtful professional. He is very good at seeking advice and he makes an effort to consider views of career staff," Robinson said.

Prior HUD chiefs of staff had resumes with deeper experience in housing issues. Laurel Blatchford, chief of staff for HUD Secretary Shaun Donovan during the Obama administration, had worked for New York City Mayor Michael Bloomberg in two capacities: first as a senior policy adviser to the deputy mayor for economic development and rebuilding and later as the chief of staff and deputy commissioner for strategy planning, policy and communications at New York City's housing department.

And chiefs of staff during the Bush years had experience on Capitol Hill, such as Robert Woodson, who previously worked as a senior aide to Sen. Kay Bailey Hutchinson, chief of staff for Rep. Bob Inglis, and as a budget analyst for the House Budget Committee.

Vacancies at the agency

Observers say exacerbating the lack of relevant experience of some of Carson's political appointees are vacancies in other important positions at the agency. Nominees for three key assistant secretary slots have not yet been confirmed.

"We are struggling because those people have not been confirmed by the Senate," Richardson said.

The Federal Housing Authority, which provides mortgage insurance to homeowners, is without a permanent leader. Right now the number two, the Deputy Assistant Secretary, is temporarily acting in that role.

Also vacant is the job of assistant secretary for policy development and research, described by an agency spokesman as the "thinking end of HUD to infuse evidence and data into the policy." A career employee is currently acting in the role. The department also has no confirmed assistant secretary for public and Indian housing, which is where the vast majority of HUD's budget goes toward some of its biggest programs, including public housing and Section 8 rental assistance programs. A career employee is temporarily acting in this role.

An agency spokesman told CNN, "Career employees can't get into the weeds making policy decisions. Important work is being done, but there is no substitute for an assistant secretary."