Washington (CNN) On President Donald Trump's 200th day in office, he still lags far behind his predecessors in staffing up his administration, both in terms of nominations and confirming those positions.

Any new administration has to fill roughly 4,000 positions across the government, more than 1,200 of which require Senate confirmation. While no administration can accomplish that task in 200 days, the nonprofit good-government group Partnership for Public Service recommends having the most important 300-400 confirmed by August recess.

Trump hasn't come close.

The President got a big boost to his progress last week when the Senate confirmed en masse more than five dozen outstanding nominees -- roughly doubling the number of nominees Trump has had confirmed.

But he still remains far behind.

As of August 4, when the Senate left town for its August recess, Trump has nominated 277 people for key posts, has had 124 confirmed, and has withdrawn eight of the nominations, according to CNN's tracker

The Partnership for Public Service has identified 577 executive branch positions as being particularly essential -- and Trump has only successfully filled about a fifth of them.

Meanwhile, his predecessor fared far better at the same point in their terms. President Barack Obama had 433 nominations and 310 confirmations at the same point, President George W. Bush had nominated 414 and had 294 confirmed, and President Bill Cilnton had 345 nominations and 252 confirmed.

Trump's rate of 45% of nominees confirmed lags behind Obama's 72%, Bush's 71% and Clinton's 73%. His nominees have also taken far longer to confirm -- an average of 54 days compared with 41, 35 and 30 respectively.

The White House has consistently placed blame for its slow pace on Democrats -- the minority party in the Senate -- arguing they've employed stall tactics to slow-walk Trump's confirmations.

Indeed, before the failure of the Senate to advance a plan to repeal Obamacare, Senate Democrats were forcing Republicans to go through all procedural steps for nominees, dragging out the process.

But part of the slowness has also been due to difficulty getting paperwork in for many of the nominees, and some announced nominations were not transmitted to the Senate for formal consideration for months. Trump also lags in naming officials amid reports that Cabinet officials and the White House have butted heads over potential candidates.

Trump has had his entire Cabinet confirmed, although when he selected John Kelly as his chief of staff late last month, he created a vacancy at the Department of Homeland Security. But experts say his slowness to fill deputy positions at agencies is equally important, as those officials handle much of the day-to-day management of government.

Partnership for Public Service President Max Stier, who has advised multiple presidents and presidential candidates, including Trump, on transitioning into office, said the President should be prioritizing filling positions if he wants to execute his agenda.

"While the pace of nominations for political appointees has picked up in recent weeks, critical leadership positions remain vacant at almost every agency and department," Stier said. "The President must prioritize getting his full team in place. Doing so will strengthen his ability to run the government, achieve his priorities and deal effectively with the inevitable crises that will take place in our complicated and dangerous world."