The Biden administration has been in office for more than five weeks now and, despite a blizzard of executive orders on immigration matters, there is only one presidential appointee in place in the Department of Homeland Security (DHS), Secretary Alejandro Mayorkas.
As of this writing, no nominees for other slots, such as deputy secretary, several assistant secretaries, and heads of agencies such as Immigration and Customs Enforcement and U.S. Citizenship and Immigration Services, have been sent to the U.S. Senate. None. Some Schedule C jobs, non-presidential-appointed political positions, have been filled, but none requiring the approval of the Senate.
This administration, unlike the previous one, believes in the positive utility of government; Trump thought he was saving money by leaving presidential appointments vacant. That is not the mindset of the Biden administration.
It is not that the new secretary does not know all of the players; during the Obama years, Mayorkas was first the head of USCIS and, later, deputy secretary of DHS. What's going on?
My sense is that the new administration is comfortable, for the moment, with career people filling these posts, as the career staff is not regarded as a problem. Most of them are far more sympathetic to the Democrats than they were to the Trump administration. I say that after half a century in Washington.
I also sense that the executive time and energy used on immigration matters has focused more on policy than personnel; thus the spate of executive orders.
DHS does not even have an acting deputy secretary. The person holding that post, a former Coast Guard admiral and one-time administrator at the Transportation Security Administration, David Pekoske, carries the title of "senior official performing the duties of the deputy secretary".
The Coast Guard, incidentally, is what you might call a migratory agency. Over the years it has been lodged in the Treasury, in the Navy in World War I, then back to the Treasury, then in the Navy again for World War II, then back to Treasury again. In 1967 it became part of the new Department of Transportation and, in 2003, it was switched to the new Department of Homeland Security.