No president in recent history has started their tenure with as many extended Cabinet vacancies as President Trump.

Why it matters: Trump has been happy to fill many of the positions with "acting" officials, saying it "gives me more flexibility." But it adds instability when so many departments are without permanent leaders — and acting secretaries don't go through the scrutiny and vetting that they'd get with Senate confirmation.

Trump has already racked up more than four times as many days with a vacant Cabinet position as any other president since Ronald Reagan at this point in their presidencies.

The White House chief of staff and vice president don't require Senate confirmation, but the other Cabinet positions do.

By the numbers: In the past six presidencies:

There have been 29 individual cabinet vacancies in the time that Trump has been in office.

individual cabinet vacancies in the time that Trump has been in office. Thirteen of them have been under Trump.

have been under Trump. His administration has also had the seven longest vacancies in the comparable timeframe.

Trump's longest vacancies:

EPA administrator : 237 days between Scott Pruitt and Andrew Wheeler.

: 237 days between Scott Pruitt and Andrew Wheeler. UN Ambassador : 157 days since Nikki Haley left (Jonathan Cohen currently acting).

: 157 days since Nikki Haley left (Jonathan Cohen currently acting). White House chief of staff : 157 days since John Kelly left (Mick Mulvaney currently acting).

: 157 days since John Kelly left (Mick Mulvaney currently acting). Secretary of Defense : 157 days since Jim Mattis left (Trump says he'll nominate Patrick Shanahan).

: 157 days since Jim Mattis left (Trump says he'll nominate Patrick Shanahan). Secretary of Homeland Security : 131 days between John Kelly and Kirstjen Nielsen (Kevin McAleenan currently acting).

: 131 days between John Kelly and Kirstjen Nielsen (Kevin McAleenan currently acting). Secretary of Veteran Affairs : 124 days between David Shulkin and Robert Wilkie.

: 124 days between David Shulkin and Robert Wilkie. Secretary of Health and Human Services: 122 days between Tom Price and Alex Azar.

The longest vacancies overall:

Office of Management and Budget director : 465 days between Jack Lew and Sylvia Burwell under Barack Obama.

: 465 days between Jack Lew and Sylvia Burwell under Barack Obama. UN Ambassador : 385 days between Bill Richardson and Richard Holbrooke under Bill Clinton.

: 385 days between Bill Richardson and Richard Holbrooke under Bill Clinton. Secretary of Commerce : 370 days between John Bryson and Penny Pritzker under Obama.

: 370 days between John Bryson and Penny Pritzker under Obama. Administrator of the Small Business Administration : 357 days between James Sanders and James Abdnor under Ronald Reagan.

: 357 days between James Sanders and James Abdnor under Ronald Reagan. U.S. Trade Representative: 340 days between Mickey Kantor and Charlene Barshefsky under Clinton.