WASHINGTON — Rising frustration with Washington and conservative electoral victories across much of the United States are feeding a movement in favor of something America hasn’t done in 227 years: Hold a convention to rewrite the Constitution.

Although it’s unlikely to be successful, the effort is more serious than ever before: Already more than two dozen states have called for a convention. There are two ways to change or amend the founding document. The usual method is for an adjustment to win approval from two-thirds of both houses of Congress and then be ratified by three-quarters of the 50 states. There have been 27 amendments adopted this way.

The second procedure is separate from Congress. It requires two-thirds of the states, or 34, to call for a convention. The framers thought this might be necessary because Congress wouldn’t be likely to advance any amendments that curtailed its powers. But this recourse has never been used.

Two states, California and Vermont, have called for a convention to overturn the Supreme Court’s Citizens United decision that permits huge amounts of unregulated money into federal campaigns. Larry Sabato, a University of Virginia political scientist, wants a convention to adopt sweeping changes, including a single six-year presidential term, and concomitant House and Senate terms to create more of a parliamentary system. Petitions to adopt term limits for members of Congress have circulated for years.