RENO, Nevada — Ted Cruz now has a Donald Trump problem.
Trump told a packed ballroom Sunday that the Texas senator's problem is actually a legal one, a "cloud" hanging over his head regarding whether his Canadian birthplace precludes him from being a "natural born citizen." In Trump's view, the issue raises "uncertainty" if Cruz were to win the Republican nomination because Democrats would file lawsuits contesting his eligibility to serve as president.
And Trump assured the crowd that he knows lawsuits. "Does anyone know more about litigation than Trump?" he asked. "I know a lot. I'm like a PhD in litigation."
Devoting the most time yet on the stump to the issue, Trump questioned why Cruz didn't renounce his Canadian citizenship earlier. "He said he didn't know about it, OK. Does he get a pass for that?" Trump then polled the crowd, who booed and yelled "no" loudly in response. Cruz formally renounced his Canadian citizenship in May of 2014 and a spokesperson for Cruz said at the time, "to our knowledge, he never had Canadian citizenship."
Cruz's situation, Trump said, reminds him of Hillary Clinton's. "It's sort of like, Hillary's got a problem too. She doesn't know whether or not she's gonna be indicted."
"She's got the cloud hanging over her head, but Ted Cruz has a real cloud hanging over his head," he added.
Trump insisted that he likes Ted Cruz, even though "a lot of people do not." And he said he was not seeking to disqualify Cruz over a technicality.
"I would rather win it straight up," he told the ballroom. "If I'm a fighter, I wanna knock the guy out, I don't wanna default because he couldn't like meet the weight class or something." But, he added, "although I'll take that too. Maybe I'd like that better, I don't know. You don't have to worry about what you look like after the fight."
Trump also targeted Cruz on issues beyond the citizenship question, hitting the Texan for changing stances on ethanol, a big issue in Iowa where the two are vying for the top spot. And he dinged Cruz for allegedly copying his plans on immigration. Trump conceded that politicians are "entitled to change" but that "you don't change with two weeks left before the election, right?"
These attacks mark a large shift in Trump's trail rhetoric, as he had previously shared a sort of political détente with Cruz. So far, Cruz is not returning fire, telling reporters in Iowa Saturday, "I like Donald Trump. I respect Donald Trump. He's welcome to toss whatever attacks he wants."
And while Trump did rile the crowd here with his tough talk on illegal immigration, Washington dysfunction and the Iran nuclear deal, he also shared his thoughts about what he called "crummy" NFL games.
In an apparent reference to Saturday night's Wild Card game between the Pittsburgh Steelers and the Cincinnati Bengals, during which a late helmet-to-helmet hit and a personal conduct penalty put Pittsburgh in field goal range to win the game, Trump declared that the "whole game" of football "is screwed up."
"Football has become soft like our country has become soft" he said, remembering the old days of "great tackles" that were "violent," "head on" and "incredible to watch." Trump alleged that now "the referees, they wanna all throw flags so their wives see them at home."
There was important campaign work behind his trip to this early state. Trump's nearly 65-minute speech began and ended with reminders to register. "Really important, over here, this state, we're way ahead but you have to go and register otherwise they're not gonna let you vote," Trump reminded the enthusiastic Nevada crowd, who will caucus for the Republican Party on February 23rd. Then, just before exiting the stage, Trump drove the point home one more time: "Register and vote! I love you all!"
This story originally appeared on NBCNews.com