Shortly after 11 a.m. on the East Coast, Sen. Marco Rubio's presidential campaign alerted the media to their candidate's latest position, inspired by the Founding Fathers and by Congress's seeming inability to pass conservative legislation.

“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," Rubio said as he campaigned in Iowa. "You know why? Because that is 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.”

Within a half-hour, radio host, lawyer and author Mark Levin had leaped up to praise Rubio. This wasn't the sort of thing Levin usually did. He frequently lumped Rubio in with GOP establishment figures he deemed traitors to conservatism. Just weeks earlier, Levin had accused the Floridian of using "Saul Alinsky tactics" to smear presidential rival Ted Cruz (R-Tex.), whom Levin frequently praises as the conservative gold standard. "Rubio and his surrogates have launched a propaganda campaign against Cruz in a deceitful attempt to distort his record," Levin said.

Today, Levin was daring the rest of the GOP to line up behind Rubio.

Rubio's campaign called the convention idea a "less-known" way to amendment the Constitution. That isn't for lack of trying by its adherents. The conservative Convention of States Project has spent the past few years gathering state legislators for strategy meetings. It has made the pitch to the American Legislative Exchange Council and gotten several Republican members of Congress on board with the concept. It has received backup from Levin, whose 2013 book, "The Liberty Amendments," delineated just what an "Article V Convention" needed to pass, and from Citizens for Self-Governance, a group founded by tea party activist Mark Meckler.

"I'm glad to see it enter the mainstream of presidential politics," Meckler said. "With over a million activists in the fight, I'm not surprised. People understand that the fix will not come from Washington, D.C., itself, and must be imposed by the people through a convention."

The praise for Rubio has surprised some earlier adopters or analysts of the Article V push. Cruz, who arrived in the Senate as the movement was getting traction, has repeatedly cited it as proof that "people are frustrated with the Washington cartel."

"Article V is a state-led initiative to amend the Constitution," Cruz spokesman Rick Tyler said. "He supports the states' right to pursue this path, which is a rigorous and controlled process. But he is running for president for precisely the same reasons states would call for an Article V convention, and that is to protect freedom and from the ever-encroaching nature of the federal government."

Former Arkansas governor Mike Huckabee, the winner of the 2008 Iowa caucuses, who has slipped behind Rubio and Cruz in that state, had been even clearer in his praise for Article V. "It is the only way we will ever be able to devolve power back from Washington to the states," he told an American Legislative Exchange Council audience this summer.

But what the cause lacked, until this week, was a head nod from a perceived presidential front-runner. Rubio's endorsement of the idea actually fell short of Levin's "liberty amendments." The radio host included eight more items in the buffet, such as Supreme Court term limits, empowering a supermajority in Congress to undo high court decisions, and the end of the 17th Amendment, which allows for direct election of senators. Cruz, not Rubio, has endorsed that first idea.

Still, Rubio earned fresh praise from, Wisconsin state Rep. Chris Kapenga, a Republican who has participated in several rounds of convention brainstorming meetings -- the most recent of them in Utah last month.

"It’s good to see that some politicians in Washington are respectful of states right," said Kapenga. "There were 32 states represented in Salt Lake City, and we'll probably finish up with a final meeting in Philadelphia this spring."

Philip Rucker contributed to this report from Waterloo, Iowa.