A lot of people feel 12 should be the limit. Many others feel 18 should be the limit. To get an agreement, a terms limit amendment should allow each state legislature to decide either 12 or 18 to be the state set maximum. That would allow parties to agree because it does not need to be uniform. There has to be enough agreement to get an amendment into a proposal state and out for ratification.
A proposal before state legislatures has the following language:
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AMENDMENT XXVIII (Federal-State Rebalancing)
To restore the foundational structure of State Legislatures to Congress, the following amendment is proposed:
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Section 1. Senators in Congress shall be subject to recall by their respective state legislature or by voter referendum in their respective state.
Section 2. Term limits for Senators in Congress shall be set by a vote in their respective state legislatures but in no case shall be set less than two terms nor more than three terms.
Section 3: The seventeenth article of amendment to the Constitution of the United States is hereby repealed.
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However, for now, the first one that is in works with Article V is a peacetime balanced budget amendment. Term limits come later.
I would disagree. Pick one or the other, but it needs to be uniform, since seniority matters for assignments.