Washington (CNN) The White House is placing responsibility for the large number of vacancies at the State Department on top diplomat Rex Tillerson and his staff, saying the secretary hasn't moved on recommended personnel to fill the openings.

The White House has suggested multiple candidates for every open senior position at the State Department and then some, a senior administration official said, including the deputy secretary and undersecretaries who help run the agency and assistant secretaries who oversee regional bureaus.

The official said Tillerson and his staff have not acted on the suggestions or, in some cases, are still considering or vetting them.

"This is state being slow," the official said.

At the same time, several State Department officials told CNN that Secretary Tillerson is considering trimming 9-10% of employees at the agency, which would be about 2300-2500 employees.

The officials cautioned that Tillerson is only starting the restructuring process, so while there are likely bureaus and employees that are going to be cut, numbers are not yet firm.

The Associated Press and other outlets reported this statistics earlier Friday.

Asked about the personnel situation Thursday, acting State Department spokesman Mark Toner defended the agency's progress on permanent staffing, saying that the process "always takes some time."

He added that Tillerson‎ and his staff have been actively vetting those potential choices.

The vacancies have concerned national security experts, frustrated lawmakers and confounded foreign diplomats, who say they no longer have a point of contact at Foggy Bottom.

The lack of staffing comes at a time when North Korea's belligerence has Asia on edge, Venezuela is imploding, Russia is expanding its hold in eastern Ukraine and US and Iranian ships have come close to clashing in the Persian Gulf.

"It's startling to my mind," said Christine Wormuth, a senior advisor for the International Security Program at the Center for Strategic and International Studies. "They need senior people and they don't have them."

Wormuth, a career civil servant for Presidents Bill Clinton and George W. Bush at the Pentagon before becoming President Barack Obama's undersecretary of defense for policy, noted there are openings across the national security spectrum.

Nearly all the senior positions under Tillerson are vacant, or are currently being filled on an acting basis by career officials who weren't chosen by the President or confirmed by the Senate. Some 200 State Department jobs require Senate confirmation.

These positions include over one third of ambassadorships, as well also nearly all undersecretary and assistant secretary positions. The White House nominated John Sullivan to fill the Deputy Secretary position last month, now held by Acting Deputy Secretary Thomas Shannon, but he needs to be confirmed by the Senate.

In a New York Times article Thursday, Tillerson spokesman R.C. Hammond indicated the secretary has plotted out a process for restructuring the agency that means senior positions will likely be filled sometime in 2018.

The Trump administration is looking to cut the State Department's budget by about 30%.

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Hammond attributed the delay to Tillerson's desire to go on a methodical "listening tour" of the department before he sets about restructing and cutting jobs and departments. Hammond, who compared the agency to the sunken Titanic ocean liner at the bottom of the ocean, told the Times that there was no sense in filling positions that may be cut later.

Some analysts assess that Tillerson's background as CEO of ExxonMobil -- the only place he's ever worked -- inclines him to see the department as just another bloated organization.

Some within the State Department, speaking anonymously to discuss the agency without fear of retaliation, point to the fact that Tillerson comes from a corporate culture that didn't always see the State Department as an asset or ally.

Others still point to his chief of staff, Margaret Peterlin, a former naval officer and Trump campaign staffer who has worked for Republican lawmakers and the Commerce Department. The White House official said Peterlin is a big part of the staffing choices and process.

‎The official specified that Peterlin is not a "White House" appointed person, but a "transition" person -- selected by Trump transition officials and then kept on by Tillerson.

The pace has not particularly pleased the White House, according to the senior official, but Tillerson has broad leeway and the White House's trust in staffing his agency.

The official did not know how long it would take Tillerson and his team to fill the open positions -- currently staffed by Obama administration holdovers -- but expected it would be "a while."

Another factor in the slow staffing pace could be the animosity between the Trump administration and much of the Republican foreign policy establishment. The White House has refused to consider a number of highly qualified people because they joined the "Never Trump" movement over differences with the Republican candidate on policy and values, as well as questions about his temperament.

"They won't look at any 'Never Trumpers' or even people who said critical things on social media," Wormuth noted. "They're also having to do a lot more recruiting for jobs than you normally see. Normally people are flinging themselves at these jobs."

In the meantime, the vacancies have drawn a highly unusual public complaint from Russia's top diplomat, who raised the issue during an April press conference with Tillerson in Moscow.

"Not all key positions in the US Department of State have been filled, and hence it is not easy to quickly receive clarification on current and future issues," Foreign Minister Sergey Lavrov chided, echoing a complaint of Washington-based diplomats from across the globe.

Lawmakers who work on foreign policy are having the same trouble. Maryland Sen. Benjamin Cardin, the top Democrat on the Senate Foreign Relations Committee, said that the Trump administration's staffing shortfalls leave him and others at a loss.

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"I don't know what the President's Iran policy is all about," Cardin said. He added that while he and others might have disagreed with the Obama administration on their Iran policies, they had people to meet with to push their position and learn what the White House was doing.

Now, he said, "We don't have an articulated position from the White House and we don't have players we can meet to discuss it with."

Sen. Bob Corker, the Tenessee Republican who chairs the Senate Foreign Relations Committee, said finding points of contact hasn't been a problem for him, however.

"Certainly, we'd like to see them staff up as quickly as possible, but I've had no problem at all talking with folks I need to talk with and getting answers," Corker told CNN. "It's fair to say we'd like for them to get more fully staffed and hopefully that will be happening soon."

But on Thursday, a group of House Democrats wrote Trump to raise concerns about the broader security questions the vacancies raise.

Noting that more than half the senior State Department positions remain unfilled, the letter said that, "nearly 100 days after your inauguration and with multiple international crises looming, it is unacceptable that these critical roles remain unfilled."

The letter was signed by Democratic members of the House Armed Services Committee, including Ruben Gallego of Arizona, Stephanie Murphy of Florida, Seth Moulton of Massachusetts, Jacky Rosen of Nevada, Colleen Hanabusa of Hawaii and Donald Norcross of New Jersey.

"It is distressing," the lawmakers wrote, "that at a time when US forces and our allies in the Asia-Pacific are gravely threatened by North Korea, there are seven US ambassador positions with key treaty allies, partners and institutions in the region that remain vacant."