donald trump iowa rally shooting sot_00001002.jpg
donald trump iowa rally shooting sot_00001002.jpg
Now playing
00:48
Trump: I could shoot somebody and not lose voters
Green Party presidential nominee Jill Stein waits to be introduced prior to a press conference at the National Press Club August 23, 2016 in Washington, DC.
Win McNamee/Getty Images
Green Party presidential nominee Jill Stein waits to be introduced prior to a press conference at the National Press Club August 23, 2016 in Washington, DC.
Now playing
01:44
Jill Stein raises millions for recount
Former Democratic US Presidential candidate Hillary Clinton speaks to staff and supporters at the New Yorker hotel after her defeat in the presidential election November 9, 2016 in New York. / AFP / Brendan Smialowski        (Photo credit should read BRENDAN SMIALOWSKI/AFP/Getty Images)
BRENDAN SMIALOWSKI/AFP/Getty Images
Former Democratic US Presidential candidate Hillary Clinton speaks to staff and supporters at the New Yorker hotel after her defeat in the presidential election November 9, 2016 in New York. / AFP / Brendan Smialowski (Photo credit should read BRENDAN SMIALOWSKI/AFP/Getty Images)
Now playing
02:14
Scientists urge Clinton to call for recount
LYNDEN, WA - MAY 07: Republican presidential candidate Donald Trump gives a speech during a rally at the The Northwest Washington Fair and Event Center on May 7, 2016 in Lynden, Washington. Trump became the Republican presumptive nominee following his landslide win in Indiana on Tuesday. (Photo by Matt Mills McKnight/Getty Images)
Matt Mills McKnight/Getty Images North America/Getty Images
LYNDEN, WA - MAY 07: Republican presidential candidate Donald Trump gives a speech during a rally at the The Northwest Washington Fair and Event Center on May 7, 2016 in Lynden, Washington. Trump became the Republican presumptive nominee following his landslide win in Indiana on Tuesday. (Photo by Matt Mills McKnight/Getty Images)
Now playing
03:25
Donald Trump's wild ride
Now playing
01:46
Trump's challenges in the Middle East
Now playing
02:47
Fact checking Trump on crimes by immigrants
Mark Makela/Getty Images/Lintao Zhang/Getty Images
Now playing
01:26
Trump vs. the tape on Obama and the protester
Now playing
01:28
Trump compares Clinton email probe to Watergate
Members of the Secret Service rush Republican presidential candidate Donald Trump off the stage at a campaign rally in Reno, Nev., on Saturday, Nov. 5, 2016. (AP Photo/John Locher)
John Locher/AP
Members of the Secret Service rush Republican presidential candidate Donald Trump off the stage at a campaign rally in Reno, Nev., on Saturday, Nov. 5, 2016. (AP Photo/John Locher)
Now playing
01:20
Donald Trump rushed off stage by Secret Service
AFP/Getty Images
Now playing
02:16
Trump reads letter from Patriot's coach at rally
US Republican presidential nominee Donald Trump speaks during rally at the Atkinson Country Club in Atkinson, New Hampshire on November 4, 2016.
Mandel Ngan/AFP/Getty Images
US Republican presidential nominee Donald Trump speaks during rally at the Atkinson Country Club in Atkinson, New Hampshire on November 4, 2016.
Now playing
01:56
Trump on US officials: 'What a group of losers'
donald trump nice and cool pensacola fl bts_00001523.jpg
donald trump nice and cool pensacola fl bts_00001523.jpg
Now playing
00:49
Trump's mantra in campaign's final week: Stay on point
donald trump nice to hillary clinton and democrats orig cm_00000000.jpg
donald trump nice to hillary clinton and democrats orig cm_00000000.jpg
Now playing
01:52
Audio of Trump praising the Clintons and Democrats
cuomo lewandowski hillary clinton email exchange newday_00002327.jpg
cuomo lewandowski hillary clinton email exchange newday_00002327.jpg
Now playing
01:28
Cuomo grills Lewandowski on Clinton email 'hypocrisy'
Now playing
01:49
Meet the other Hillary Clinton and Donald Trump

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

(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.

RELATED: Trump: I could ‘shoot somebody and I wouldn’t lose voters’

Most legal experts have agreed with Cruz’s assessment, but the issue has never been settled in federal court, and Trump noted Saturday that he would have legal standing to sue Cruz over the issue as an opponent for the Republican presidential nomination.

Trump began suggesting earlier this month that Cruz’s Canadian birth could endanger Republicans’ chances of winning the White House, arguing that Democrats would sue to keep Cruz out of the White House.

Cruz held dual citizenship until he officially renounced his Canadian citizenship in 2014.

Trump on Saturday also reprised a line he used against Cruz on Twitter just a day earlier, noting that Cruz “could run for the prime minister of Canada.”

“And I wouldn’t even complain because he was born in Canada,” Trump said.

Trump’s comments Saturday came nine days before Iowans are set to head to the caucuses to vote in the first contest of the primary cycle.

Trump and Cruz are neck and neck in recent polls, and both candidates have amplified their attacks against each other in recent weeks.

Trump this week launched his first attack ad against Cruz, suggesting the Texan has been inconsistent on immigration, a contrast with Trump’s hardline position on the issue.

Trump on Saturday also raised the subject of Cruz’s previously undisclosed loans he received from Goldman Sachs and Citibank to finance his political campaign that propelled him to the Senate.