Congress has been doing pro-forma sessions (gaveling in and & out every 3 days during breaks). When Obama attempted to appoint some NLRB members during such a pro-forma session, arguing that it was bogus because no one was really "there", he was sued and lost at the SCOTUS because the SCOTUS indicated that Congress made its own rules and if they said that pro-formas were enough to be considered "in session" and not "adjourned", then so be it.
Usually the congressional "locals" (MD/VA/WV/DE) are in the area and can do it.
Article I
Section 5.
Each House shall be the judge of the elections, returns and qualifications of its own members, and a majority of each shall constitute a quorum to do business; but a smaller number may adjourn from day to day, and may be authorized to compel the attendance of absent members, in such manner, and under such penalties as each House may provide.
Each House may determine the rules of its proceedings, punish its members for disorderly behavior, and, with the concurrence of two thirds, expel a member.
Each House shall keep a journal of its proceedings, and from time to time publish the same, excepting such parts as may in their judgment require secrecy; and the yeas and nays of the members of either House on any question shall, at the desire of one fifth of those present, be entered on the journal.
Neither House, during the session of Congress, shall, without the consent of the other, adjourn for more than three days, nor to any other place than that in which the two Houses shall be sitting.
<...>
Section 7.
All bills for raising revenue shall originate in the House of Representatives; but the Senate may propose or concur with amendments as on other Bills.
Every bill which shall have passed the House of Representatives and the Senate, shall, before it become a law, be presented to the President of the United States; if he approve he shall sign it, but if not he shall return it, with his objections to that House in which it shall have originated, who shall enter the objections at large on their journal, and proceed to reconsider it. If after such reconsideration two thirds of that House shall agree to pass the bill, it shall be sent, together with the objections, to the other House, by which it shall likewise be reconsidered, and if approved by two thirds of that House, it shall become a law. But in all such cases the votes of both Houses shall be determined by yeas and nays, and the names of the persons voting for and against the bill shall be entered on the journal of each House respectively.
If any bill shall not be returned by the President within ten days (Sundays excepted) after it shall have been presented to him, the same shall be a law, in like manner as if he had signed it, unless the Congress by their adjournment prevent its return, in which case it shall not be a law.
Every order, resolution, or vote to which the concurrence of the Senate and House of Representatives may be necessary (except on a question of adjournment) shall be presented to the President of the United States; and before the same shall take effect, shall be approved by him, or being disapproved by him, shall be repassed by two thirds of the Senate and House of Representatives, according to the rules and limitations prescribed in the case of a bill.
https://www.law.cornell.edu/constitution/articlei
As a sidenote - if they did just wait it out to let it go into effect, there would still be a shutdown over the 10 days until the CR would "legally" go into effect without an explicit signature UNLESS someone invokes an obscure rule that will "stop the clock" (although I don't know if it has ever been "stopped" that long).
= new reply since forum marked as read
