Republican presidential candidate Ben CarsonBenjamin (Ben) Solomon CarsonOvernight Energy: Political appointee taking over as Interior IG | Change comes amid Zinke probe | White Houses shelves coal, nuke bailout plan | Top Dem warns coal export proposal hurts military Overnight Energy: Political employee to replace Interior inspector general amidst investigations| White House pauses plan to bail out coal and nuclear| Top Armed Services Dem warns Trump coal plan on military bases could hurt national security HUD political appointee to replace Interior Department inspector general MORE is warning rival Ted CruzRafael (Ted) Edward CruzFive takeaways from Cruz, O'Rourke's debate showdown O'Rourke's mom discusses past Dem votes after labeled 'lifelong Republican' by son Live coverage: Cruz faces O'Rourke in Texas debate showdown MORE that he must hold his campaign staff accountable for suggesting the retired neurosurgeon was dropping out of the 2016 race. 

"I call on Senator Cruz to take decisive action at a senior level within his campaign or I fear this culture of destructive behavior will only continue," Carson said in a fundraising email Thursday evening. 
 
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The escalation of the ongoing fallout between Cruz and Carson comes after Breitbart News published a voicemail received by a Cruz precinct captain in Iowa on the night of the Iowa caucus that told her to "tell any Ben Carson voters that for tonight, uh, that they not waste a vote on Ben Carson, and vote for Ted Cruz." 
 
A second voicemail said Carson was suspending his campaign. 
 
The voicemails, which were left at 7:07 p.m. and 7:29 p.m., according to Breitbart, came after Carson's campaign had clarified that while he was returning to Florida briefly, he was not dropping out of the 2016 election. 
 
Referring to a frequent campaign slogan from Cruz, Carson added on Thursday that "if Senator Cruz truly wants to defeat the Washington Cartel, he must be willing to hold people accountable for adopting deceptive Cartel tactics."
 
Carson's comments, and the Cruz campaign voicemail, are the latest in an escalating battle between the two. 
 
Carson has repeatedly accused Cruz's campaign of spreading rumors during the Iowa caucuses that the retired neurosurgeon was quitting the presidential race, suggesting the Texas Republican negatively impacted his campaign.
 
Cruz's campaign has defended itself, saying it was only sharing news reports. 
 
Catherine Frazier, a spokeswoman for Cruz's campaign, doubled down Thursday, telling Breitbart that "the voicemails are in line with the reports that were made at that time."