Republican presidential candidate Ben CarsonBenjamin (Ben) Solomon CarsonTo end homelessness, follow the science Ben Carson attended indoor fundraiser where attendees didn't wear masks: report Building the Dream: We're in This Together MORE is warning rival Ted CruzRafael (Ted) Edward CruzGOP clears key hurdle on Barrett's Supreme Court nomination, setting up Monday confirmation Texas and North Carolina: Democrats on the verge? Senate GOP to drop documentary series days before election hitting China, Democrats over coronavirus 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."