Ronny L. Jackson, President Trump’s nominee for VA secretary. (Nicholas Kamm/AFP/Getty Images)

“DEMOCRATS ARE obstructing good (hopefully great) people wanting to give up a big portion of their life to work for our Government,” President Trump tweeted last week. “They are ‘slow walking’ all of my nominations — hundreds of people. At this rate it would take 9 years for all approvals!” Echoed by Trump surrogates and other Republicans, this was just the latest of Mr. Trump’s regular attempts to shift the blame for his understaffed government onto Senate Minority Leader Charles E. Schumer (D-N.Y.). And foot-dragging Democrats surely bear some responsibility. But as Mr. Trump’s latest nomination fiasco unfolds at the Department of Veterans Affairs, it becomes ever more obvious where most of the blame lies.

More than 450 days after Mr. Trump’s inauguration, well over half of 656 key positions remain unfilled, according to a running Post tally. This pace is well behind that of the past two administrations.

Mr. Trump and other Republicans complain that Senate Democrats have insisted on lengthy confirmation proceedings for an extraordinary number of presidential nominees. Ever since then-Senate Majority Leader Harry M. Reid (D-Nev.) triggered the “nuclear option” in 2013, reducing the approval threshold for presidential nominees to a simple majority, the minority party’s main leverage has been its ability to force a time-consuming cloture process. Democrats have undoubtedly used this leverage, forcing cloture on more than 80 of Mr. Trump’s executive and judicial picks. Over the equivalent period in President Barack Obama’s first term, it was forced on 12 nominees; in President George W. Bush’s, none.

Democrats point to the inexperience and ethical shortcomings of many nominees. Sometimes opposition was justified, as in the case of Environmental Protection Agency nominee Scott Pruitt, a longtime climate-change denier who has proved himself a reckless spender, and Housing and Urban Development nominee Ben Carson, who knew embarrassingly little about housing and has had his own ethical stumbles. In other cases, Democratic opposition appears unjustified; 18 judicial and executive nominees endured the time- ­consuming cloture process but won confirmation by extremely lopsided margins. For example, the nomination of Rebecca Grady Jennings for a District Court judgeship was not controversial, yet she was forced to go through the cloture process anyway.

But it is more than a little rich for Republicans to complain about Democratic intransigence. They liberally forced cloture on nominees in Mr. Obama’s second term, after Mr. Reid invoked the nuclear option, and they have since removed other avenues for Democrats to object to Trump nominees.

More to the point, most of the vacancies stem from Mr. Trump’s slowness to nominate — and his firing of those already confirmed. Poor vetting and impulse picks, as in the case of Navy Rear Adm. Ronny L. Jackson, the president’s choice to be his (second) veterans affairs secretary, have led to time wasted on nominees who struggle or are withdrawn. More than 200 key positions still lack nominees, including many in the State Department and the Justice Department.

If Mr. Trump had his own house in order, his attacks on Democrats might carry more weight. But his failure to nominate promptly, to vet carefully and to choose nominees with appropriate qualifications bespeaks a contempt for government that demeans him and his administration.