Donald Trump on Tuesday and again on Wednesday morning suggested the fact that Ted Cruz was born in Canada could pose problems for Republicans -- raising the specter of questions about his eligibility for the presidency. This is well-worn territory, including by Trump himself, so we thought it worth re-posting what we have written before.

Sen. Ted Cruz (R-Tex.) announced his intention to run for president in the 2016 election during a speech at Liberty University in Lynchburg, Va. (AP)

First, here's the root of the issue:

Cruz, like a couple of presidential candidates before him, faces a alleged hurdle to running for president in that it's not 100 percent clear that he's a "natural-born citizen," as the Constitution requires presidents to be.

Cruz's mother was a U.S. citizen when he was born, and current U.S. law extends citizenship to anyone born to a U.S. citizen, regardless of where the birth takes place. The question is whether citizenship is the same thing as being a "natural-born citizen."

Legal scholars generally agree that Cruz meets that requirement, and Cruz's office agrees. But it also remains somewhat untested in the courts.

While no president-elect has formally tested the "natural-born citizen" requirement, several have run for president with that question hanging over their candidacies.

Democrats in 1967 suggested that Republican George Romney would not be eligible to serve as president, because he was born to U.S. citizens in Mexico. But a New York Law Journal piece at the time argued forcefully that he would be, and that seemed to put the issue to rest. (Romney's primary campaign wound up imploding.)

Sen. John McCain (R-Ariz.), the GOP's nominee in 2008, was born in the Panama Canal Zone to U.S. citizens. After he secured the party's nomination, the Senate in 2008 passed a resolution stating that McCain was indeed a natural-born citizen.

In fact, this debate dates back to President Chester A. Arthur and the original "birther" controversy. While Arthur is listed as being born in Vermont, some argued that he was born in Canada and thus ineligible to be president.

The nonpartisan Congressional Research Service has even weighed in on the issue, writing in November 2011 that people born to U.S. citizens in foreign countries "most likely" qualify as natural-born citizens.

"The weight of more recent federal cases, as well as the majority of scholarship on the subject, also indicates that the term 'natural born citizen' would most likely include, as well as native born citizens, those born abroad to U.S. citizen-parents, at least one of whom had previously resided in the United States, or those born abroad to one U.S. citizen parent who, prior to the birth, had met the requirements of federal law for physical presence in the country," wrote Jack Maskell.


Cruz on stage at Liberty University. (AP Photo/Andrew Harnik)

Cruz's office thought enough of the issue in 2013 to have the senator release his birth certificate and later renounce his Canadian citizenship. Here's my take from then on how Cruz "birthers" are different from Obama "birthers":

And for the few in the birther community, they see hypocrisy. Why are the media not denouncing those who question Cruz's eligibility in the same way they have denounced the so-called "birthers" who continue to question Obama's?

The reason? Because about the only thing these two situations have in common is that they involve a birth certificate and a presidential candidate.

Questions about Cruz's eligibility have everything to do with interpretation of the law; the questions about Obama's eligibility had everything to do with a dispute over the underlying facts — more specifically, conspiracy theories about whether the president was actually born in the United States, as he claimed, and whether he somehow forged a birth certificate that said he was born in Hawaii.

In Cruz's case, nobody is disputing the underlying facts of the case — that Cruz was born in Canada to a Cuban father and a mother who was a United States citizen. As we wrote back in March (2013), that makes him a U.S. citizen himself, but it's not 100 percent clear that that is the same thing as a "natural born citizen" — the requirement for becoming president.

Most scholars think it's the same thing, and the Congressional Research Service said in 2011 that someone like Cruz "most likely" qualifies to run for president. But to this point, there is no final word from the courts, because while foreign-born candidates have run — including George Romney and John McCain — none of them has actually won and had his eligibility challenged.

Obama was also born to a mother who was a U.S. citizen, meaning if he was in fact born outside the United States, the situations might be parallel. But birthers weren't making a legal argument about Obama; they were arguing the facts about where he was born and accusing him of perpetrating a massive fraud.

Some will accuse the media of instituting a double standard when it comes to these two cases because Cruz is a Republican and Obama is a Democrat. But nobody is accusing Cruz of lying about his past as part of a vast conspiracy to become president.

It's just not an apples-to-apples comparison.

And here is my Post colleague Robert Barnes's piece on what top legal experts from both sides say:

Two of the top lawyers for the Obama and Bush administrations agree on this: Sen. Ted Cruz can become president. Legally speaking, anyway.

Paul D. Clement, former solicitor general for President George W. Bush, and Neal Katyal, former acting solicitor general for President Obama, penned a piece for the Harvard Law Review tackling the question of what the Constitution means when it says that the president must be at least 35 years old, a U.S. resident for at least 14 years and a “natural born Citizen.”

“All the sources routinely used to interpret the Constitution confirm that the phrase ‘natural born Citizen’ has a specific meaning: namely, someone who was a U.S. citizen at birth with no need to go through a naturalization proceeding at some later time,” they wrote. “And Congress has made equally clear from the time of the framing of the Constitution to the current day that, subject to certain residency requirements on the parents, someone born to a U.S. citizen parent generally becomes a U.S. citizen without regard to whether the birth takes place in Canada, the Canal Zone, or the continental United States.”

...

The First Congress, they noted, established that children born abroad to U.S. citizens were themselves citizens at birth “and explicitly recognized that such children were ‘natural born citizens.’

“The actions and understandings of the First Congress are particularly persuasive because so many of the Framers of the Constitution were also members of the First Congress,” Katyal and Clement write. “That is particularly true in this instance, as eight of the eleven members of the committee that proposed the natural born eligibility requirement to the Convention served in the First Congress and none objected to a definition of “natural born Citizen” that included persons born abroad to citizen parents.”