The truce is no more.
Presidential candidate Ted Cruz had once steadfastly maintained that he wouldn't engage in attacks against GOP frontrunner Donald Trump, as the two enjoyed rising polls and heavy crossover support from GOP primary voters.
But after the two began jockeying in earnest for frontrunner status - and after Trump unleased a series of attacks on Cruz's immigration stance and his eligibility to be president - the Texas senator is hitting back, albeit in a way that he hopes won't alienate the most strident of Trump backers.
In an interview on the Howie Carr radio show Tuesday, Cruz suggested that Trump should play "New York, New York" at his rallies - rather than "Born in the USA," which Trump has recently started airing as a clear dig at Cruz's Canadian birthplace.
"I think he may shift in his new rallies to playing 'New York, New York' because Donald comes from New York and he embodies New York values," Cruz said. "And listen, The Donald seems to be a little bit rattled."
The rhetorical slap appears to be an effort to head off the possibility that Trump's attacks on Cruz's status as a "natural born citizen" could hurt Cruz with his own coalition.
Trump repeated those charges at a rally Tuesday night in Cedar Falls, Iowa, suggesting that he did not initiate the attack but that Cruz must address his "problem" regarding his eligibility to serve as president.
A Cruz aide, earlier in the day, denied to NBC News that the line of attack has hurt the candidate, saying of the charge "We haven't seen any evidence it's resonating."
In the Tuesday radio interview, Cruz also responded to Trump's comment that "you don't see a lot of evangelicals coming out of Cuba," a reference appearing to question Cruz's faith.
"Any time someone is attacking your faith that starts to suggest they're getting really nervous about what's happening in the race," Cruz said before repeating that he hopes "not to engage in the mudslinging."
Earlier Tuesday, Cruz drew ties between supporters of Hillary Clinton and those who back Trump.
Citing Trump's references to Harvard Law professor Laurence Tribe, who has cast doubt on Cruz's eligibility to be president, Cruz branded Tribe "a liberal left-wing judicial activist Harvard Law professor who is a huge Hillary supporter."
"Gosh, why are Hillary's strongest supporters backing Donald Trump?'" he asked reporters in New Hampshire.
"It seems the Hillary folks are very eager to support Donald Trump and the attacks that are being tossed my direction," he added.