I still believe the Constitution prohibits it, take a close look at the punctuation in Section 3, which I've emphasized in the paragraph below:
Section. 3. Clause 1: New States may be admitted by the Congress into this Union; but no new State shall be formed or erected within the Jurisdiction of any other State; nor any State be formed by the Junction of two or more States, or Parts of States, without the Consent of the Legislatures of the States concerned as well as of the Congress.
So, we have 3 parts of the clause:
1. States can be added
2. You can't make a new State out of part of an existing State
3. You can't make a new State out of parts or the whole of two or more States
And we have 1 exclusion:
1. "Something" is allowed if you get State Legislature & Congress to agree to it. (But what is that "something"?)
The three parts of the clause are separated by semi-colons, not commas. The exclusionary language appears in the section of the clause pertaining to "combining" two or more States to make a new one. It doesn't apply to the first two parts of the clause (in fact it doesn't make any sense at all when applied to the first part).
Based on my interpretation, we're tilting at windmills trying to get this through.
I believe you'll find I am correct in the interpretation of the US Constitution when you check the American history and see that Maine was formed from Massachusetts, and Vermont was formed from New York. It should be noted that these two states were formed at a time many of the delegates that authored the US Constitution were still living, serving in Congress, and they had no problem interpreting what the Constitution required.
Here's a link to a map that shows the original thirteen colonies:
http://library.thinkquest.org/10966/map.shtml?tqskip1=1
Vermont statehood: 1791
Maine statehood: 1820
I see no reason we would want to interpret the Constitution any differently than those that originated the document.
One additional thought about the Congressional approval requirement necessitated by the US Constitution. I mentioned Congress had approved such a split when statehood was granted California, but I hadn't mentioned our current national political situation which also favors statehood, and would make that prior approval a moot point.
There is a Republican majority in both the Houses of Representatives and the Senate. Can you imagine either of these two chambers not approving a split that would increase their numbers in both chambers, and thus increase their majority?