Supporters of a national constitutional convention, as provided for in Article V of the U.S. Constitution, have gained the support of 27 state legislatures for the idea. They need 34.

Republicans and Democrats are at war both with each other and within their own parties over the proposal. Some Republicans want such a convention for the purpose of getting a balanced-budget amendment.

Some Democrats also want a convention for the purpose of overturning the U.S. Supreme Court's Citizens United ruling and regulating political-campaign spending.

Some members of both parties fear that a convention might get out of hand, producing unforeseen results. History says these Cassandras are correct.