Momentum is building behind what would be an unprecedented effort to amend the U.S. Constitution, through a little-known provision that gives states rather than Congress the power to initiate changes.

At issue is what's known as a "constitutional convention," a scenario tucked into Article V of the U.S. Constitution. At its core, Article V provides two ways for amendments to be proposed. The first – which has been used for all 27 amendment to date – requires two-thirds of both the House and Senate to approve a resolution, before sending it to the states for ratification. The Founding Fathers, though, devised an alternative way which says if two-thirds of state legislatures demand a meeting, Congress “shall call a convention for proposing amendments.”

The idea has gained popularity among constitutional scholars in recent years -- but got a big boost last week when Michigan lawmakers endorsed it.

Michigan matters, because by some counts it was the 34th state to do so. That makes two-thirds.

In the wake of the vote, California Republican Rep. Duncan Hunter pressed House Speaker John Boehner on Tuesday to determine whether the states just crossed the threshold for this kind of convention. Like Michigan lawmakers, Hunter's interest in the matter stems from a desire to push a balanced-budget amendment -- something that could potentially be done at a constitutional convention.

“Based on several reports and opinions, Michigan might be the 34th state to issue such a call and therefore presents the constitutionally-required number of states to begin the process of achieving a balanced budget amendment,” Hunter wrote.

“With the recent decision by Michigan lawmakers, it is important that the House – and those of us who support a balanced budget amendment -- determine whether the necessary number of states have acted and the appropriate role of Congress should this be the case."

If two-thirds of the states indeed have applied, the ball is presumably in Congress' court to call the convention.

But Article V is rather vague, and it's ultimately unclear whether 34 states have technically applied. In the past, states like Oregon, Utah and Arizona have quietly voted to approve the provision in their legislature.

But some of the 34 or so have rescinded their requests. Others have rescinded, and then re-applied.

Alabama rescinded its request in 1988 but in 2011, lawmakers again applied for a convention related to an amendment requiring that the federal budget be balanced. It was a similar story in Florida in 2010.

Louisiana rescinded in 1990 but lawmakers have tried several times, unsuccessfully, to reinstate the application since then.

It's unclear whether the applications still count in these scenarios.

Some constitutional scholars like Gregory Watson, an analyst in Texas, say once states ask, there may be no take-backs.

“There is a disagreement among scholars as to whether a state that has approved an application may later rescind that application,” Watson told The Washington Times. “If it is ultimately adjudicated that a state may not rescind a prior application, then Ohio’s 2013 application for a Balanced Budget Amendment convention would be the 33rd and Michigan’s 2014 application would be the 34th on that topic.”

Others say if a state changes its mind, it can no longer be part of the 34.

Even if the requisite number of states have applied, questions remain about how such a convention would work -- and whether, as Michigan wants, such a convention could be limited to only discussing a balanced-budget amendment.

It still may be a long shot, but some analysts are warning about the unintended consequences of such a move.

In Louisiana, Budget Project Policy Analyst Steve Spire argued against the state's resolution, saying the convention could permanently damage the nation’s political system.

The last time there was a successful amendment was more than four decades ago – the 26th Amendment which changed the voting age to 18. States ratified the 27th Amendment on congressional pay increases, but it took more than 200 years to do it.