Further to my musings on constitutional limits on “acting” officials, a self-professed “Very Unimportant Government Lawyer With Nothing Better To Do” draws my attention to 5 USC 3346, which imposes a statutory limit of 210 days or so in which an official can be “acting” in the absence of a nomination to a post.
The statute doesn't explain who takes over if the 210+ day period lapses — I presume it's the next in line for the job, (unless the President designates someone else).
(a) Except in the case of a vacancy caused by sickness, the person serving as an acting officer as described under section 3345 may serve in the office -
(1) for no longer than 210 days beginning on the date the vacancy occurs; or (2) subject to subsection (b), once a first or second nomination for the office is submitted to the Senate, from the date of such nomination for the period that the nomination is pending in the Senate.
(b)(1) If the first nomination for the office is rejected by the Senate, withdrawn, or returned to the President by the Senate, the person may continue to serve as the acting officer for no more than 210 days after the date of such rejection, withdrawal, or return.
(2) Notwithstanding paragraph (1), if a second nomination for the office is submitted to the Senate after the rejection, withdrawal, or return of the first nomination, the person serving as the acting officer may continue to serve -
(A) until the second nomination is confirmed; or (B) for no more than 210 days after the second nomination is rejected, withdrawn, or returned.
(c) If a vacancy occurs during an adjournment of the Congress sine die, the 210-day period under subsection (a) shall begin on the date that the Senate first reconvenes.
Hard-core separation of powers dorks will want to take a look at Doolin Security Savings Bank v. Office of Thrift Supervision 139 F.3d 203 & 156 F.3d 190, wherein among other fascinating things, a diverse panel of the DC Circuit agrees unanimously that the head of the Office of Thrift Supervision is an “Officer of the United States” and that the 210 day clock starts when an acting person starts in on his job and not when the vacancy occurs.
(Adlaw mavens may be startled at the discussion of harmless error in a separation of powers case. I was.)