Presidential candidate Sen. Marco Rubio (R-FL) recently announced his support for a “convention of the states,” an idea heavily promoted by conservative media figures, particularly conservative radio host and author Mark Levin. Constitutional scholars and Supreme Court Justices have said that if enacted, the idea dangerously opens up the U.S. Constitution to outside influences.

Rubio announced his support for the initiative during December campaign stops in Iowa, saying, “One of the things I'm going to do on my first day is office is I will put the prestige and power of the presidency behind a constitutional convention of the states.” He described it as “the only way that we are ever going to get term limits on members of Congress or the judiciary and that is the only way we are ever going to get a balanced-budget amendment.”

His official campaign website followed up with a post saying, “Marco supports establishing a Convention of the States with the sole purpose of passing amendments to limit the power of the federal government: like implementing term limits, requiring a balanced budget, and sending power out of Washington, back to the states.” The campaign promised, “On the campaign trail, Marco's going to keep talking up the Convention of the States.” The site also embedded a post from Levin highlighting Rubio's endorsement of his idea.

The idea of a constitutional convention has gotten attention from other Republican politicians as well. Governor Greg Abbott (R-TX) recently endorsed the convention of the states, describing it as “the Texas Plan to restore the Rule of Law and return the Constitution to its intended purpose.” He appeared on Levin's radio show and on The Kelly File on Fox News to discuss his decision.

The convention of the states proposal is based on Article V of the U.S. Constitution, which states that Congress can call a convention for proposing amendments if two-thirds of state legislatures formally make a proposal. This is a departure from how the 27 previous amendments to the Constitution have passed, where Congress has passed the amendments and then sent them down to the states to be ratified.

While the idea has been at the fringes of the conservative movement for decades, Levin gave a huge boost to the proposal in his 2013 book The Liberty Amendments. In an interview with the conservative news site CNSNews, Levin said his proposal “is the only way out” because “The federal government, Congress, the Supreme Court, the president, the bureaucracy, they are not going to reform themselves, they are not going to limit their activities. Only we can--through our state representatives from the bottom up.”

Conservative media outlets promoted Levin and the book's ideas. Sean Hannity turned over an entire episode of his Fox News show (with a studio audience) to interviewing Levin about The Liberty Amendments.

Rush Limbaugh urged his listeners to buy the “wonderful book,” and said “something” like a convention of the states “is going to be necessary, because the Constitution is broken.”

On his radio show, Glenn Beck said Levin had “made that case” for a convention. In a story published on Breitbart.com and FrontPageMag.com, Spyridon Mitsotakis wrote that Levin “has now shown us a way that we the people can save ourselves.” Michelle Malkin called the book “a bold, provocative manual for restoring the American republic and righting the balance of powers.” Hugh Hewitt told his listeners to go into bookstores and “If you can't find it, demand that they put it up front.” On Fox's Your World, host Neil Cavuto interviewed Levin and recommended reading the book “to get some historical perspective of what the hell is going on.” On The Five, co-host Eric Bolling called the book “fantastic.”

Before he had declared his candidacy, Donald Trump called it “a truly great & important book.”

Coinciding with the release of Levin's book, a campaign called Convention of the States, which is a project of another group called Citizens for Self-Governance , was formed in order to organize and promote the concept at the state level. In a blog post, Citizens for Self-Governance said the Convention of the States is “a grassroots plan to implement the important ideas Mark Levin has begun to publicly advocate.” The post also promoted Levin's Hannity appearance: “Tune in to watch Levin on Hannity Friday, then go visit our website at www.ConventionOfStates.com and see how you can get involved and play a part in history."

Those two groups are led by Michael Farris and Mark Meckler. Meckler was the co-founder of the group Tea Party Patriots. Meckler recently described Rubio's endorsement as a “game-changer” for his campaign and hailed him for pushing the idea into “the mainstream of presidential politics.”

Levin told Conservative Review “I have wholeheartedly endorsed the Convention of the States project” and “I serve on its Legal Board of Reference because they propose a solution as big as the problem. And they are promoting state applications for a convention for the purpose of limiting the scope, power and jurisdiction of the federal government. And that's what needs to be done.”

The Convention of the States website also features testimonials from conservative media figures like Hannity, Beck, Allen West, and Sarah Palin.

In an April 2015 report on the movement to call a new convention with the aim of passing a balanced budget amendment, the Washington Post reported on the possible pitfalls of this amendment process. They note, “the founding document is silent on how such a convention would operate,” and add, “There's no indication that a convention could be limited to just one topic. Hypothetically, delegates could take up any issue they wanted, from reinstating Prohibition to eliminating the direct election of senators. More extreme scenarios envision delegates revisiting the 13th Amendment, which banned slavery, or inserting corporate giveaways into the Constitution.”

Figures on both the left and right have pointed out that such a convention would be dangerous.

Harvard Law professor Laurence Tribe said the process would be “putting the whole Constitution up for grabs.”

Even conservative Justice Antonin Scalia has described the idea as dangerous, noting, “I certainly would not want a constitutional convention. Whoa! Who knows what would come out of it?”

The late Justice Arthur Goldberg also criticized the idea, saying, “There is no enforceable mechanism to prevent a convention from reporting out wholesale changes to our Constitution and Bill of Rights.” In 1983 Chief Justice Warren Burger wrote, a “Constitutional Convention today would be a free-for-all for special interest groups.”

Slate's Jamelle Bouie writes, “It's worth noting that this renewed push” for a constitutional convention “comes at a time the United States is becoming younger, browner, and more liberal. For a movement whose electoral health is tied to an aging population of white conservatives, it's increasingly now or never for right-wing ideologues, or at least, moves that block liberals from achieving their goals.”