*Editor's note: This story has been updated throughout. 

HUDSON, N.H. — Ted Cruz on Tuesday went further than ever in needling Donald Trump, suggesting Democrats are behind the billionaire's questions about his citizenship. 

Speaking with reporters after a rally here, the U.S. senator from Texas was asked what he thought of Trump citing Harvard law professor Laurence Tribe's analysis that Cruz might be ineligible to be president. Trump has pounced on Cruz's Canadian birth to cast doubt on whether he is a natural-born citizen.

“I will say it is more than a little strange to see Donald relying on as authoritative a liberal, left-wing, judicial activist Harvard law professor who is a huge Hillary supporter," Cruz replied. "It starts to make you think, ‘Gosh, why are some of Hillary’s strongest supporters backing Donald Trump?’"

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Cruz then suggested Democrats were supporting Trump as a way of propping up a Republican they believe they can beat in the general election.

"You know, the last couple of elections, you’ll recall the Democrats got the nominee they wanted to run against in the general election," Cruz said. "It seems the Hillary folks are very eager to support Donald Trump and the attacks that are being tossed my direction.'"

Cruz sought to tie Trump even closer to Democrats later Tuesday afternoon when asked by a radio host about Clinton's statement that Trump was "basically a Democrat before he was a Republican." 

“I would say Hillary would know well how to identify Democrats," Cruz told the Boston-based host, Howie Carr. "She has been a partisan Democrat herself obviously. She and Donald know each other well."

Taken together, the remarks represent Cruz's sharpest turn yet on Trump, whom he has refused to criticize for months, even as the billionaire has sharpened his attacks against Cruz. The two are now locked in a tight race in Iowa, the first-in-the-country caucus state.

Trump has been raising questions about whether Cruz is a natural-born citizen, which the Constitution requires for someone to serve as president. Cruz has insisted the legal question is straightforward: He argues his mother's U.S. citizenship (she's from Delaware) makes him a natural-born citizen, even if he was born in Calgary and his father is from Cuba.

Tribe, who taught constitutional law to Cruz at Harvard, has said the issue is not as cut and dry, recently telling The Guardian that questions about Cruz's eligibility to be president are "murky and unsettled." Trump has favorably cited Tribe's analysis more than once, calling the professor a "constitutional expert, one of the best in the country," during a rally Monday in New Hampshire.

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Tribe, viewed as one of the top liberal law professors in the country, has a long history of donating to Democratic candidates and causes. He did not immediately respond to a request for comment. 

Cruz is back in the Granite State for the first time in two months. He plans to hold another event later Tuesday afternoon, a town hall in Londonderry.