(Justin Hayworth/AP Photo)

Sen. Ted Cruz on Tuesday said that he initially didn't know he was Canadian citizen because he didn't think it was important to consult an immigration lawyer to find out.

"That's something I'd never talked to an immigration lawyer [about] because, frankly, it didn't matter," Cruz, R-Texas, told KTRK reporter Tom Abrahams at a Houston airport today. "I was a citizen by birth and was focused on doing my job."

Cruz on Sunday released a copy of his birth certificate, which showed definitively that he was born in Calgary, Alberta, Canada in 1970. Cruz's mother, an American citizen, was born in Delaware. His father, in Cuba.

Cruz is widely thought to be a potential 2016 presidential contender. And most experts believe that he is eligible to run for president because his mother was a U.S. citizen at the time of his birth.

"When I as a kid, when I was four, we moved from Calgary back down to Houston; I grew up in Houston," Cruz said. "And when I was a kid my mother told me, if I ever wanted, I could affirmatively choose to claim Canadian citizenship because I was born there."

Cruz said he got a U.S. passport, never did anything to claim his supposed Canadian citizenship and "thought that was the end of it" until the Dallas Morning News in a story Sunday spoke to a Canadian immigration lawyer who said Cruz has Canadian citizenship.

In a statement on Monday night, Cruz said he would renounce his Canadian citizenship. He added today that, as a U.S. senator, it is "only appropriate" to be "only an American."

"You know, I think there's been a lot of silliness on this issue," Cruz said. "When this story broke and a lot of these outlets ran with it, I joked that it must have been a very, very slow news day."

President Obama has also had to deal with his own "birthers," who suggested without concrete evidence that the president - born in the U.S. state Hawaii to an American mother - was born in Kenya.