Aides and allies of the insurgent senator from Texas acknowledged in interviews this week that the campaign has been damaged by attacks on Cruz’s integrity from Donald Trump and Marco Rubio. They have pointed to a series of questionable tactics by the Cruz camp, including calls to voters suggesting that candidate Ben Carson was dropping out and the sharing of an inaccurate video suggesting Rubio had disparaged the Bible.

The video flap prompted Cruz to abruptly fire his chief spokesman, Rick Tyler, who posted the clip on social media, on Monday in an attempt to put his candidacy back on course. But the troubles continued Tuesday, when the campaign halted the sale of merchandise by a street artist whose social-media accounts include controversial and sometimes racist messages.

Cruz also weathered another wave of attacks from Trump on the eve of the Nevada caucuses. Trump told a rally in Sparks, Nev., that Cruz is “like a little baby — soft, weak little baby. . . . But for lying, he’s the best I’ve ever seen.”

Cruz and his aides say the accusations of deception are simply false. But with the issue dominating media coverage for more than a week, aides and supporters now acknowledge that the attacks have started taking a toll.