Sanders fires back at Trump: 'Never tweet'
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Sen. Bernie SandersBernie SandersSenators introduce bipartisan infrastructure bill in rare Sunday session Bipartisan infrastructure win shows Democrats must continue working across the aisle 'The land is us' — Tribal activist turns from Keystone XL to Line 3 MORE (I-Vt.) fired back at Donald TrumpDonald TrumpSenators introduce bipartisan infrastructure bill in rare Sunday session Gosar's siblings pen op-ed urging for his resignation: 'You are immune to shame' Sunday shows - Delta variant, infrastructure dominate 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 ClintonClintons, Stacey Abrams meeting Texas Democrats Biden says Russia spreading misinformation ahead of 2022 elections Highest-ranking GOP assemblyman in WI against another audit of 2020 vote 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.