Ted Cruz's presidential bid is in turmoil after repeated allegations of unsavory campaign tactics by his Republican rivals, leading some key supporters to call for a shake-up in the candidate's message and strategy a week ahead of the crucial Super Tuesday primaries. 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...