There would be a seat of the government encompassing White House, Capitol, SCOTUS, etc. - can’t be any larger than 100 sq mi. - no matter how small it got it would still retain 3 EV unless you passed a constitutional amendment.
Then a new state running from Baltimore to Prince William County - New Columbia? Marva? It looks like it would take in at least 7 US House seats (4 from MD - Montgomery, Prince George, Baltimore, and a connector; 2 from VA plus old DC would get one)
Then Old Maryland - 4 US House seats at the most.
Then Old Virginia - 8 or 9 US House seats
Your idea would require a constitutional amendment.
The above plan would require only Congressional approval plus MD and VA legislatures.
I agree. But I think youre more likely to get a constitutional amendment than approval by VA and MD. The Red States outnumber the Blue States. They would support my proposal. The Blue States would likely not since they lose ground in the Senate.
Also I am not convinced that your legislative proposal really makes DC a state. It makes the surrounding area a separate state. But DC is still DC under your proposal. You cant change that without changing the Constitution.