[SteveH]

A slightly less ambitious way to go might be to target a single county or two in Texas and secede from that state, forming a new state in the process. (Is there a provision in the acceptance of Texas to the Union which permits that?... not a Texas expert, obviously...)

[SteveH]

Also, some Texas counties I heard are sparsely populated...

[ganesha]

Section 3. New states may be admitted by the Congress into this union; but no new states 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.

Article 4 section 3 U.S. Constitution

[#3Fan]

(Is there a provision in the acceptance of Texas to the Union which permits that?... not a Texas expert, obviously...)

There's no such thing as an admission agreement. The Constitution is the law of the land. Texas may have thought they had an admission agreement, but unless the Constitution was amended before Texas was admitted, too late.