After a week on the receiving end of attacks by the billionaire businessman, including charges that the senator isn't eligible to be president because he was born in Canada, Cruz launched a high-risk tactic that has befell every other Republican that tried it -- attacking The Donald.
The change from Cruz's seven-months-old, turn-the-other-cheek strategy, which was on display just 24 hours ago, involves aggressively highlighting Trump's ties to the Democratic Party. The Texas senator is also making an electability argument, saying he beats Hillary Clinton in national polls while Trump doesn't.
And in an interview with Massachusetts radio station WRKO, Cruz made his most personal charge yet, saying Trump "embodies New York values," and portraying Trump as out of step with an increasingly southern, religious GOP.
Campaigning Tuesday across New Hampshire, where Trump holds a dominant lead, Cruz responded much more sharply to Trump's taunts than he has in the past. For the past week, Cruz has tried to brush off Trump's broadsides as political silliness, but on Tuesday he suggested Trump's comments reflected his cozy relationship with prominent Democrats.
"I would say Hillary would know well how to identify Democrats. She has been a partisan Democrat herself," Cruz said on WRKO, when asked about Clinton's recent statement that Trump used to be a Democrat. "She and Donald know each other well, and I do think it's interesting that Hillary Clinton's key supporters are doing everything they can to echo Donald's attacks on me."
Later on Tuesday, he repeatedly mocked Trump's wealth in a mock State of the Union address, and then told conservative radio host Hugh Hewitt that he doesn't get his national security knowledge from "the Sunday shows," a clear joust at a Trump comment that has been ridiculed by other Republicans as well.
And since the real estate mogul last week began suggesting the Texas senator may not be eligible to be president
given his birth, Cruz has also begun to needle Trump's style of campaigning.
Asked in Decorah, Iowa last week how he differs from Trump, Cruz offered that he is campaigning in the "Iowa way" -- an aggressive schedule of retail politicking, which Trump has not done to date.
Trump has also raised questions about the faith of Cruz, who identifies as southern Baptist, like his Cuban-born father.
"Not many evangelicals come out of Cuba," Trump recently quipped.
Cruz countered in his WRKO interview.
"Listen, any time somebody's attacking your faith, it starts to suggest they're getting really nervous about what's happening in the race," Cruz said.
Trump's main argument has been that Cruz is constitutionally unable to assume the White House,
a position bolstered this week
by prominent Harvard Law professor Laurence Tribe, who said he agreed with Trump.
Still, the gloves have not completely come off: While Trump has criticized Cruz's policy positions on ethanol mandates and portrayed himself as the true leader on border security, Cruz has yet to directly attack the New Yorker's bona fides on those issues. But Cruz's comments Tuesday are the latest tension point between the top two Republican candidates in Iowa, where polls show them neck and neck.
Speaking to reporters earlier in the day in Hudson, Cruz said again that he found it curious that Trump's support on the Canadian question came from Democrats. Cruz's campaign believes that virtually all constitutional scholars, except Tribe, say he is eligible for the presidency since he was born to a mother who is an American 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 told reporters in Hudson, New Hampshire, Tuesday. "It starts to make you think, gosh, why are Hillary's strongest supporters backing Donald Trump?"
Cruz then added that Democrats are eager to see Trump as the GOP nominee and suggested that should raise a red flag.
"You know, the past couple of elections we saw the Democrats thrilled that they got the nominee they wanted to run against in the general election," he said. "And it seems the Hillary folks are very eager to support Donald Trump and the attacks that are being tossed my direction."