AUSTIN, Texas -- Canada-born U.S. Sen. Ted Cruz has made good on a promise to renounce his birth country's citizenship, amid speculation he could make a run at the White House in 2016.

Spokeswoman Catherine Frazier said Cruz's action became official May 14 and that the Texas senator received written confirmation at his home in Houston on Tuesday. She said the Republican "is pleased to have the process finalized."

"Being a U.S. Senator representing Texas, it makes sense he should be only an American citizen," Frazier said in an email.

Cruz, 43, was born in Calgary, Alberta, in 1970, while his parents were working in the oil business there. His mother, Eleanor, is from the U.S., while his father, Rafael, is a Cuban who didn't become a U.S. citizen until 2005.

Though he has been in office only about 18 months, Cruz helped lead last year's partial government shutdown and has become a conservative grass-roots champion.

Amid questions last year about his eligibility to be president should he decide to run, Cruz released his birth certificate to the Dallas Morning News -- and said he was surprised to learn he was a dual Canadian-U.S. citizen.

Upon learning that he'd received it at birth, he promised to formally give it up. Months passed before Cruz hired an immigration attorney to help him with the process.

Frazier provided a copy of Cruz's Certificate of Renunciation, which certifies that Rafael Edward Cruz "has formally renounced Canadian citizenship and pursuant to the Citizenship Act will cease to be a citizen."

The U.S. Constitution says only a "natural born Citizen" may be president. Legal scholars, however, generally agree the description covers foreign-born children of U.S. parents.

Previous foreign-born Americans -- notably Republicans John McCain and George Romney -- have run for president with some mention, but no serious challenges, of their eligibility.

Some conservatives claimed President Barack Obama was born in Kenya and thus not eligible to be U.S. president. Obama is an American citizen; his father was Kenyan, his mother American.

Cruz, who has made frequent trips to Iowa, New Hampshire and South Carolina, the first three states to hold presidential contests, has refused to say if he plans to run for president.