For most of his presidential campaign and much of his presidency, President Barack Obama endured erroneous claims that he was born in Kenya rather than the United States. He released the short form of his birth certificate to prove he was born in Hawaii. Then the long form. The conspiracists died down, but they remained.

Now, the first candidate to throw his hat in the ring for the 2016 presidential contest, Sen. Ted Cruz, R-Texas, was born outside the United States, a fact he willingly offered.

Cruz, who was born in Canada, has maintained there are no constitutional barriers that prevent him from running. And so far the challenges to his candidacy are few and far between.

So can Cruz run? He likely can, just as Obama could have even if he were born in Kenya -- which, again, he most certainly wasn’t.

Cruz — full name: Rafael Edward Cruz — was born in Calgary, Canada, in 1970. His family was living there because his father was working for the oil industry at the time. They moved when he was four. Cruz grew up in Texas and graduated from high school there, later attending Princeton University and Harvard Law School.

In 2013, the first-term senator — already considered a prospective presidential candidate — released his birth certificate , which shows his mother was born in Delaware and his father was born in Cuba. (A situation similar to Obama, whose mother was born in Kansas and father was African.)

Most legal scholars maintain that Cruz is in the clear despite his Canadian birthplace.

But is the issue 100 percent settled? Not exactly.

What the constitution says

We first looked into this issue in 2013 but decided to look again now that Cruz has formally announced. As we found back then, the constitutional requirements for a presidential candidate created by the Founding Fathers are concise but not readily clear.

Two provisions are obvious: The candidate must be 35 years of age and a resident of the United States for 14 years. The third qualification: He or she must be a "natural born citizen."

What does it mean to be a "natural born citizen"?

Most legal experts contend it means someone is a citizen from birth and doesn’t have to go through a naturalization process to become a citizen.

If that’s the definition, then Cruz is a natural born citizen by being born to an American mother and having her citizenship at birth. The Congressional Research Service, the agency tasked with providing authoritative research to all members of Congress, published a report after the 2008 election supporting the thinking that "natural born" citizenship means citizenship held "at birth."

There are many legal and historical precedents to strongly back up this argument, experts have said.

Those precedents were the subject of a recent op-ed in the Harvard Law Review by two former solicitor generals of opposing parties, Neal Katyal and Paul Clement, who worked for Presidents Barack Obama and George W. Bush, respectively. They wrote that "natural born" had a longstanding definition dating back to colonial times.

British common law recognized that children born outside of the British Empire remained subjects, and were described by law as "natural born," Katyal and Clement wrote.

"The framers, of course, would have been intimately familiar with these statutes and the way they used terms like ‘natural born,’ since the (British) statutes were binding law in the colonies before the Revolutionary War,’" they said.

Additionally, the first Congress of the United States passed the Naturalization Act of 1790, just three years after the Constitution was written, which stated that children born abroad to U.S. citizens were, too, natural born citizens. Many members of the inaugural Congress were also authors of the Constitution.

Incidentally, this isn’t the first time the qualifications of a candidate have come into question. George Romney, the father of Mitt Romney who ran for president as a Republican in 1968, was born in Mexico. Barry Goldwater, the 1964 GOP presidential nominee, was born in Arizona before it was a state. Neither candidate’s campaign was derailed by citizenship challenges.

More recently, Sen. John McCain, R-Ariz., faced questions about his eligibility because he was born in the Panama Canal Zone while his father was stationed there.

Interestingly, McCain’s potential Democratic opponents — Obama and then-Sen. Hillary Clinton — co-sponsored a Senate measure to settle McCain’s eligibility. The April 2008 resolution said, "John Sidney McCain, III, is a 'natural born Citizen' under Article II, Section 1, of the Constitution of the United States." It passed unanimously.

The Supreme Court’s silence

The reason a question still remains even after Romney, Goldwater and McCain is because the Supreme Court — the ultimate arbiter of constitutional questions — has never directly ruled on the citizenship provision for presidential office holders. And that means a note of uncertainty remains.

Some have unsuccessfully challenged the qualifications of presidential contenders, but courts have been reluctant to address the issue. Several citizens filed lawsuits asking the court to rule on whether McCain was a natural born citizen early in 2008 , but the legal challenges didn’t go anywhere.

"We know from the McCain lawsuits, courts don’t want to touch this," said Sarah Duggin, a professor of law at Catholic University who has researched this issue extensively. "It very well may be that the courts would refuse to go near this. There are so many issues."

Partly, Duggin said, citizens who triggered the lawsuits in the past don’t have standing to sue.

But courts may be forced to weigh in if one of two things occur: A state, citing Cruz’s Canadian birthplace, tries to exclude him from the ballot; or another presidential candidate challenges Cruz’s eligibility.

Neither scenario is likely, though there may be a potential wild card this go around: Donald Trump.

The business tycoon and television personality was one of the most outspoken birthers who claimed Obama was born in Kenya, not Hawaii. While others who erroneously questioned Obama’s birthplace have been silent on Cruz, Trump, a fellow Republican, has not.

"It’s a hurdle. Somebody could certainly look at it very seriously," Trump told a New York news outlet Monday. "He was born in Canada. If you know and when we all studied our history lessons, you are supposed to be born in this country, so I just don't know how the courts will rule on this."

Trump is also exploring a presidential bid. If he did enter the race, it could give him standing to launch a lawsuit against Cruz.

The courts could still punt on the question, Duggin said. They could consider this a political question, in which case it would be out of bounds for the courts to interject.

But until it happens, or until a constitutional amendment clarifies matters, we won’t know for sure.

"No matter how many people opine," Duggin said, "There’s always going to be that issue."