WASHINGTON — (CNN) Donald Trump pressed forward Monday with his attacks on Texas Sen. Ted Cruz, who is running neck and neck with Trump in Iowa, the first state to vote in the Republican primary.

“Ted Cruz has a problem,” Trump said Monday morning in New Hampshire, the state that will vote for a Republican nominee a week after Iowa.

That problem, of course, is whether Cruz’s birth in Canada affects his eligibility to serve as President — a question Trump has strategically raised in multiple interviews and rallies in recent weeks.

The Constitution requires a candidate be a “natural born citizen” to be eligible to be President, a qualification most legal scholars agree includes individuals born abroad to an American parent — like Cruz.

The issue has never been tested in federal court, a fact Trump reminded his audience of on Monday: “It’s not a settled matter.”

Trump suggested that he was simply offering some friendly advice for his competitor, who has remained on friendly terms with Trump throughout the campaign.

But even if Cruz moves to settle the matter in court, as Trump suggested, the billionaire added that “it doesn’t matter.”

“You can’t have a nominee who is going to be subject to being thrown out as the nominee,” Trump said.

Trump also hit Cruz on immigration, suggesting the candidate had adopted his hardline positions on border security and deportation of undocumented immigrants.

Cruz defended his immigration plans on Sunday to CNN’s Jake Tapper on “State of the Union.”

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