Sen. John McCain speaks to reporters on Capitol Hill in Washington in May. (Brett Carlsen/AP)

Before the President Obama "birther" controversy and long before the Ted Cruz version, there was John McCain.

Questions in 2008 about the presidential eligibility of McCain, who was born in the Panama Canal Zone to two American parents, never reached the level of Obama or even Cruz, and McCain was helped out by his fellow senators and even Democratic presidential candidates agreeing that he was eligible.

But they were certainly there, cropping up throughout 2008. And in many ways, they were treated as much more legitimate than even the Cruz questions are today.

McCain on Wednesday did his Senate foe, Cruz, few favors by suggesting that it's not clear Cruz is eligible to be president. The suggestion carries much more weigh because McCain himself faced very similar questions.

NBC News Justice correspondent Pete Williams wrote about the McCain questions while the 2008 GOP primary was still going, on Feb. 29, 2008, emphasizing that it was a "serious question with no clear answer":

Sen. John McCain, R-Ariz., and his advisers are doing their best to brush aside questions — raised in the liberal blogosphere — about whether he is qualified under the Constitution to be president.  But many legal scholars and government lawyers say it's a serious question with no clear answer.

The problem arises from a phrase in the Constitution setting out who is eligible to be president.  Article II, which also specifies that a person must be at least 35 years old, says "No person except a natural born Citizen" can be president.

Sen. McCain is undoubtedly a citizen. He was born on Aug. 29, 1936, in the Panama Canal Zone, and Congress has specifically provided that anyone born there of U.S. parents, as he was, is a citizen.  Indeed, the general rule is that anyone born of U.S. parents outside the United States is a citizen.

But is John McCain a natural born citizen? The Constitution does not define the term further, and legal scholars say the notes of the Constitution's drafters shed little light on what they meant. It seems clear only that the founders wanted to make certain that whoever was president would be loyal to the U.S. alone and not to some other country.  But the term "natural born citizen," many scholars say, was not in common use at the time the Constitution was written.

Here's The Washington Post on May 2, 2008, after the Senate passed a nonbinding resolution stating that McCain was eligible:

Jurists on both sides of the political divide, consulted by the McCain campaign, insist that the issue is clear-cut. They argue that McCain is a natural-born citizen because the United States held sovereignty over the Panama Canal Zone at the time of his birth, on Aug. 29, 1936; because he was born on a U.S. military base; and because his parents were U.S. citizens.

But Sarah H. Duggin, an associate law professor at Catholic University who has studied the "natural born" issue in detail, said the question is "not so simple." While she said McCain would probably prevail in a determined legal challenge to his eligibility to be president, she added that the matter can be fully resolved only by a constitutional amendment or a Supreme Court decision.

"The Constitution is ambiguous," Duggin said. "The McCain side has some really good arguments, but ultimately there has never been any real resolution of this issue. Congress cannot legislatively change the meaning of the Constitution."

Senators sympathetic to McCain's position, including Democrats Claire McCaskill (Mo.) and Patrick J. Leahy (Vt.), dropped an earlier attempt to quell the eligibility controversy with legislation. McCaskill acknowledged in an interview that there is "no way" to completely resolve the question short of a constitutional amendment, a cumbersome process which could not be concluded before November.

As that last paragraph demonstrates, the resolution didn't completely quell the issue. And indeed, it came up again repeatedly, including in this July 11, 2008, New York Times piece:

In the most detailed examination yet of Senator John McCain’s eligibility to be president, a law professor at the University of Arizona has concluded that neither Mr. McCain’s birth in 1936 in the Panama Canal Zone nor the fact that his parents were American citizens is enough to satisfy the constitutional requirement that the president must be a “natural-born citizen.”

The analysis, by Prof. Gabriel J. Chin, focused on a 1937 law that has been largely overlooked in the debate over Mr. McCain’s eligibility to be president. The law conferred citizenship on children of American parents born in the Canal Zone after 1904, and it made John McCain a citizen just before his first birthday. But the law came too late, Professor Chin argued, to make Mr. McCain a natural-born citizen.

“It’s preposterous that a technicality like this can make a difference in an advanced democracy,” Professor Chin said. “But this is the constitutional text that we have.”

Several legal experts said that Professor Chin’s analysis was careful and plausible. But they added that nothing was very likely to follow from it.

As the three clips above show, the idea that McCain wasn't eligible to serve as president were not so clearly and flatly dismissed as settled issues or conspiracy theories.

Coverage of the Cruz matter, by contrast, generally acknowledges that he's very likely eligible, as legal scholars agree. But those same scholars said during the McCain debate and today that it's still not 100 percent clear, since there is no final legal ruling.

So why is there more emphasis on this issue with Cruz? Well, one reason is certainly the similarities to the Obama birther controversy (even though the situations aren't really that analogous). Another is that a man named Donald Trump is raising the issue. And a third is that there are many more people covering the 2016 election and many more stories being written about it. The political media landscape is much more focused on these momentary controversies and inside-baseball debates.

But the questions about McCain were certainly there — and were treated as being serious.