Story highlights "It's so nasty though," Trump said. "Ugh, I'm so good at that stuff."

Trump has repeatedly suggested that Cruz may not be eligible to serve as president because he was born in Canada

Sioux Center, Iowa (CNN) Donald Trump on Saturday floated the idea of suing his presidential rival Sen. Ted Cruz, who was born in Canada, over his eligibility to run for president.

"Should I do it just for fun?" Trump asked at a campaign rally here.

"It's so nasty though," Trump added. "Ugh, I'm so good at that stuff."

Trump has repeatedly suggested that Cruz may not be eligible to serve as president because he was born in Canada, raising the question of whether Cruz meets the Constitutional requirement that the president be a natural-born citizen.

Cruz has insisted that he meets that bar because he was born to an American mother, making him an American citizen by birth.

Read More