'They're going to sue his a-- off': Donald Trump launches new wave of Ted Cruz attacks

Real-estate tycoon Donald Trump tore into Sen. Ted Cruz (R-Texas) with renewed vigor at a Tuesday-night rally, the day after Cruz bested him in the Iowa caucuses.

Trump, during a campaign speech, repeatedly attacked his top Republican presidential rival on a host of issues, including the mogul's favorite attack line: Cruz's birth in Canada.

"What kind of people do we have running for office?" Trump said after bashing Cruz's honesty for a while in Milford, New Hampshire.

"No, it's honestly really, really dishonest. And I think I know why. You know why? Because he was born in Canada!" he said.

Cruz was born in Canada to an American mother, and most legal experts believe he meets the Constitution's requirement that presidents be "natural born" citizens. But Trump frequently warns that if Cruz becomes the GOP nominee, Democrats would sue and potentially disqualify him from the presidency.

"He gets the nomination, they're going to sue his a-- off," Trump said Tuesday.

Trump said this after seizing on a new topic with which to criticize Cruz: retired neurosurgeon Ben Carson's accusation that Cruz played "dirty tricks" on the night of the Iowa caucuses.

At the time, Carson reportedly signaled that he was speaking early Monday and flying home to Florida, which caused some Cruz supporters to publicly speculate that Carson was withdrawing from the race. Rep. Steve King (R-Iowa), one of Cruz's most prominent surrogates, wrote on Twitter: "Carson looks like he is out. Iowans need to know before they vote. Most will go to Cruz, I hope."

Carson, who came in fourth in the Iowa caucuses, blasted the "deceit and dirty tricks and lies" during a speech before his supporters there. Cruz apologized to Carson on Tuesday and said his team should have promoted Carson's statement denying the rumors.

Trump compared the rumors with Cruz's running anti-Trump ads claiming Trump supported Obamacare. Cruz has gone out of his way to highlight Trump's past support for liberal-leaning policies, including on healthcare, but Trump has promised to repeal Obama's signature healthcare legislation.

"These are dishonest people, these politicians," Trump said, also attacking Cruz for a provocative mailer the senator's campaign sent some voters in Iowa. "These are worse than real-estate people in New York, I'm telling you. No, no, these are truly dishonest people."

At another point in his speech, Trump also implicitly accused Cruz of stealing his idea to build a wall along the Mexican border. And he further criticized Cruz and other GOP candidates for taking big-money contributions from special interests.

"If you look at Ted Cruz, he's got tremendous money from the oil companies. He's going to take care of the oil companies. He's going to take care of Wall Street, even though he didn't report his loans," Trump said, boasting that he was investing his personal fortune into his campaign.

"Now, those people are 100% going to - like a little puppet - they're going to take care of those interests," Trump added, speaking broadly. "With me, I have nobody. I just want to take care of you. I just want to do the right thing."