Washington (CNN) Nearly 2,000 appointed positions in the administration of President Donald Trump remain vacant, leaving many agencies with large staffing gaps waiting to be filled, according to data reviewed by CNN.

Meanwhile, Trump is noticeably behind the last three presidents when it comes to securing the confirmation of his Cabinet and other top appointments that require Senate approval.

Trump complained about the pace of confirmations Friday in a speech at the Conservative Political Action Conference in Washington. He told the crowd the administration was "setting records" for Senate delays and that he didn't like seeing "all those empty seats" at his Cabinet meetings.

The figures below show Trump indeed has had the least successful run of Senate confirmations since George H.W. Bush back in 1989.

Only 14 Trump appointees have been confirmed as of February 21, while President Barack Obama had twice as many top-level appointments confirmed by that date. George W. Bush and Bill Clinton also bested Trump in getting the Senate to approve their choices, according to the Partnership for Public Service, a Washington-based nonprofit.

George H.W. Bush only had 11 of 21 nominations confirmed by then, although Bush also kept on three Cabinet members from the prior Reagan administration.

Many current vacancies don't require Senate approval

But the administration's ability to install political appointees goes far beyond those that require Senate confirmation. High-ranking roles like Cabinet officials draw the most public attention -- and at times, controversy. But every president also gets to fill hundreds of other jobs throughout the federal government.

For many such roles, Senate opposition is a non-factor: Those appointees can be named directly by the president or his top officials.

Yet, as of Thursday, Trump had at least 1,987 vacancies within his new administration, most of which did not require Senate confirmation, according to data from tracking service Leadership Directories reviewed by CNN.

(Hover over the bars below to reveal the vacancies at each agency.)

The White House did not respond to a request for comment on its pace of appointments, and the data reviewed by CNN did not include federal judges.

The vacancies examined by CNN included direct presidential appointments as well as what are known as "Schedule C" appointments -- a class of political appointees the government describes as "making or approving substantive policy recommendations" and jobs that "can be performed successfully only by someone with a thorough knowledge of and sympathy with the goals, priorities, and preferences" of the administration.

Those appointments are generally chosen by a president's aides or Cabinet officials. They do not require Senate approval.

According to the Leadership Directories data, there are more than 4,000 positions classified as direct presidential or Schedule C political appointments. About two-thirds of those roles are hired at the sole discretion of the president, while about a third require Senate confirmation.

The nearly 2,000 current vacancies in the Trump administration mostly require no Senate confirmation. While Trump has only 14 new people confirmed by the Senate, other jobs requiring Senate approval are still being carried out by people left from the Obama administration, often serving on an interim basis.

According to the data collected by Leadership Directories, the Trump administration currently has about 400 vacant roles that require Senate confirmation, another roughly 400 direct presidential appointments sitting empty that don't require confirmation, and about 1,200 Schedule C vacancies that similarly do not require Senate approval.

Trump may be having difficulty filling slots because some Republicans are reluctant to serve, and others are being passed over because they were critical of Trump during the campaign.

Elliott Abrams, a veteran of the Reagan and George W. Bush administrations, was nixed by Trump for the No. 2 job at the State Department after he found out about criticism Abrams made of Trump during the campaign. Until then, he had been a leading contender for the still unfilled position.

Placing the blame

Trump has blamed the slow pace of filling his Cabinet in particular on Senate Democrats, who have used procedural measures to force the full length of time allowed for nearly all confirmations, slowing down the process.

"I still have people out there waiting to be approved and everyone knows they're gonna be approved. It's just a delay, delay, delay, it's really sad," Trump told the audience at the CPAC gathering on Friday. "We still don't have our Cabinet. I assume we're setting records for that. That's the only thing good about it is we're setting records. I love setting records. But I hate having a Cabinet meeting and I see all these empty seats."

Unable to stop any nominees without Republican support given the move to a 51-vote threshold by former Democratic Senate leader Harry Reid, Democrats have also resorted to tactics like refusing to show up for committee votes, forcing Republicans to reconvene and pass the nominee by suspending the rules the following day.

Democrats counter that many of Trump's nominees have had trouble getting their paperwork in and have not answered questions in a timely manner.

Environmental Protection Agency Administrator Scott Pruitt was the most recent Trump nominee to receive Senate approval when he was confirmed last week over Democratic opposition.

First choices fall out of favor

But as Trump continues to search for more names to fill out his nascent administration, he's also already seeking replacements.

This week, Trump named Army Lt. Gen. H.R. McMaster to fill the role of national security adviser.

Trump has also already named a replacement to be secretary of labor after the first nominee, fast food executive Andrew Puzder, withdrew his nomination in the face Republican opposition. Alexander Acosta, dean of the Florida International University College of Law, was named less than 24 hours after Puzder withdrew.

The nominee for secretary of the Army, Vincent Viola, also withdrew from consideration, citing trouble disengaging from his business ties. A replacement has yet to be named.