CRESCO, Iowa — Questions surrounding Ted Cruz's citizenship, long dormant in the presidential race, are suddenly moving to the forefront, prompting the Texas senator to explain the circumstances of his Canadian birth with just weeks until the first nominating contest. 

As with many controversies this primary season, billionaire Donald Trump sparked the brouhaha, saying in an interview published Tuesday that Cruz's birth on foreign soil could be a "big problem" for the GOP. In the days since, Cruz has insisted his eligibility for the presidency is not in doubt while dismissing Trump's pot stirring — and reporters' nagging questions about it — as a trivial sideshow. 

"People will continue to make political noise about it, but as a legal matter it’s quite straightforward," Cruz told reporters before a stop Wednesday in Rock Rapids, the morning after reports surfaced suggesting North Korea had tested a nuclear weapon. “As last night’s events demonstrated, I think there are serious issues facing the American people, serious issues to be decided in this election, and that’s where our focus is going to stay."

The Constitution requires a person to be a "natural born citizen" to run for president, which is generally accepted to mean that at least one of the person's parents is a U.S. citizen. Legal experts largely agree Cruz meets that definition because, although he was born in Canada to a father from Cuba, his mother was from Delaware. His campaign sought to erase any doubt by releasing her birth certificate Friday. 

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"As the court has defined it, as history and practice has defined it, he meets it," said Lino Graglia, a law professor at the University of Texas at Austin. However, Graglia warned that the issue is "not really" settled law, as Cruz has insisted. 

"The Constitution says natural born citizenship," added Graglia, who specializes in constitutional law. "What it means depends entirely on what the court says it means, like everything else in the Constitution.” 

Trump has sought to capitalize on that uncertainty on more than one occasion in recent days, most notably advising Cruz to settle the matter in court to head off any potential challenges to his eligibility during a general election. Cruz has flatly declined the advice. 

The debate is unfolding in headlines as the senator barnstorms Iowa in a six-day, 28-county bus tour. In recent weeks, Cruz has eclipsed Trump for the number one spot in Hawkeye State polling.

"If you can't beat 'em, disqualify 'em, it seems," the pro-Cruz super PAC Keep the Promise I said in a statement on Trump's citizenship gambit. 

"I don’t think the average Republican voter in Iowa is concerned about Ted Cruz’s citizenship. I think they have more important things on their mind,” said Jamie Johnson, a prominent Christian conservative activist in Iowa who worked for Rick Perry's 2016 presidential campaign. 

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“They’re just not bringing it up to me," Johnson added. "Nobody’s talking about it.”

At least one group is buzzing about Cruz’s citizenship in ways helpful and not: the other members of the GOP field.

Among those calling Cruz's citizenship a non-issue are at least a few Republican rivals: former Florida Gov. Jeb Bush, retired neurosurgeon Ben Carson and U.S. Sen. Marco Rubio of Florida. Even Mitt Romney, the 2012 GOP nominee, weighed in Friday, suggesting Cruz's critics are rummaging in the wrong alley. 

"Cruz is a ‘natural born citizen.' Obama too. Even George Romney," Romney tweeted. "This isn't the issue you're looking for."

Not every Republican candidate is looking to take the issue off the table, though. Former Hewlett Packard CEO Carly Fiorina said Thursday she found it “odd” that Cruz did not renounce his Canadian citizenship until 2014, calling his presidential eligibility a “legitimate issue.” U.S. Sen. Rand Paul of Kentucky has agreed with Trump’s assessment that Cruz could be a target for a flurry of litigation.

“Is it a concern that people will sue over him not being born in the country?” Paul asked earlier this week on Fox News radio. “You know, it hadn’t been a big discussion yet, and I think this will begin the discussion of it."

Meanwhile, Democrats are doing little to put out the fire. On Thursday, U.S. House Minority Leader Nancy Pelosi would not say whether she believes Cruz is a natural born citizen. A day earlier, White House press secretary Josh Earnest was asked if President Barack Obama, who faced his own barrage of questions about his eligibility to be president, was enjoying seeing a member of the rival party deal with the same scrutiny. 

"I don’t know if he does, but I sure do," Earnest replied. "Look, it would be quite ironic if after seven or eight years of drama around the president’s birth certificate, if Republican primary voters were to choose Sen. Cruz as their nominee — somebody who actually wasn’t born in the United States and only 18 months ago renounced his Canadian citizenship."

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Iowans do not appear to be too concerned about Cruz's citizenship. The subject has come up only once in more than a dozen Q-and-As with audiences: during a town hall Friday morning in Webster City, where a woman asked Cruz to "discredit all the hubbub" surrounding his citizenship.

"I have never breathed a breath of air on this planet when I was not a citizen," Cruz declared after explaining the circumstances of his birth to the woman. "The reason it's being talked about right now," he added, is his rising stock in the race.

After a town hall later Friday in Osage, Mason City retiree Bob Harris said he's not worried about Cruz's eligibility for the presidency, especially after seeing Cruz explain his situation during a recent TV interview. 

Trump's "just trying to raise doubts and just trying to distract people from the real issues," Harris said. "There's nothing to it." 

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