Sanders fires back at Trump: 'Never tweet'
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Sen. Bernie SandersBernie SandersSanders: Trump was right about 'trying to end endless wars' Democrats battle over best path for Puerto Rico Bernie Sanders says he disagrees with Tlaib's call for 'no more police' MORE (I-Vt.) fired back at Donald TrumpDonald TrumpBiden administration still seizing land near border despite plans to stop building wall: report Illinois House passes bill that would mandate Asian-American history lessons in schools Overnight Defense: Administration says 'low to moderate confidence' Russia behind Afghanistan troop bounties | 'Low to medium risk' of Russia invading Ukraine in next few weeks | Intelligence leaders face sharp questions during House worldwide threats he MORE after the brash GOP presidential nominee said Sanders "sold out" and abandoned his supporters.  

"Never tweet," Sanders posted on Twitter Monday night, just minutes after he ended his speech at the Democratic National Convention, during which he warned that having Trump in the White House would threaten the progressive policies that drove his campaign against presumptive Democratic presidential nominee Hillary ClintonHillary Diane Rodham ClintonChelsea Clinton: Pics of Trump getting vaccinated would help him 'claim credit' Why does Bernie Sanders want to quash Elon Musk's dreams? Republican legislators target private sector election grants MORE.
Trump has knocked Sanders since he endorsed Clinton. He took aim at the Vermont senator while he was speaking in Philadelphia, saying he "totally sold out to Crooked Hillary Clinton." 
"All of that work, energy and money, and nothing to show for it! Waste of time," he added. 
Trump has tried to play up frustration among progressive voters as Democrats try to project unity at their four-day event. He also said Monday that former Sanders backers were welcome to join his campaign.