Senate Minority Leader Chuck Schumer said Monday that President Donald Trump should blame himself for the number of vacancies remaining in the federal government that require confirmation to fill.

"If the president is looking for someone to blame on the slow pace of confirmations, he needs only to look in the mirror," the New York Democrat said in a statement. "There are more than 500 Senate confirmable positions. Even though it is now June, the administration has failed to select a nominee for 442 of them."

The president, Schumer charged, "ought to roll up his sleeves and get to work rather than pointing false fingers of blame."

Earlier Monday, Trump attacked the minority party on the matter, saying Democrats "are taking forever to approve my people, including Ambassadors."

"They are nothing but OBSTRUCTIONISTS! Want approvals," the president tweeted.

The large number of political–appointee vacancies in the federal government has previously been the subject of a partisan blame game.

Vacancies at the State Department, led by former Exxon Mobil CEO Rex Tillerson, have been of particular concern among some lawmakers, including a group of Democratic senators who last month sent a letter to Trump saying "we need a fully staffed and funded State Department to protect U.S. interests and values abroad."

On Sunday, Politico reported that "Trump has yet to nominate a single assistant secretary [of state] … Instead, career civil servants – 'acting' assistant secretaries – are filling the jobs until their replacements are nominated."

Trump's lambasting of Democrats as "obstructionists" followed the acting ambassador at the U.S. Embassy in London posting a tweet that appeared to counter Trump's post-terror attack criticisms of London Mayor Sadiq Khan.