Despite previously throwing some praise in Bernie Sanders' general direction, presumptive GOP nominee Donald Trump had nothing but criticism following the Vermont senator's official endorsement of former rival Hillary Clinton. "I am somewhat surprised that Bernie Sanders was not true to himself and his supporters," Trump tweeted Tuesday. "They are not happy that he is selling out!"

Trump also tweeted a video originally posted by the @TeamTrump Twitter account, highlighting Sanders' prior criticisms of Clinton's presidential qualifications:

Sanders was quick with the clap-back, referencing that time Trump refused to debate him in California:

Trump had previously suggested similarities between himself and Sanders, telling the audience at an MSNBC town hall in February that he was "very similar" to Sanders. "[Sanders] knows our country is being ripped off big league—big league—on trade," Trump said. "The problem is he can't do anything about it."

In April, Trump expressed his support of Sanders' criticism of Clinton's policies. "He said some things about her that were so incredible—incredible—and so incredibly bad," Trump said shortly after sweeping 5 primaries, Reuters reported. According to Trump, Sanders had simply been "telling the truth."

Trump appeared to be tapping into these supposed similarities again Tuesday, urging Sanders supporters to join him on the GOP side:

"I have come here today not to talk about the past, but to focus on the future" Sanders said during a Clinton campaign event in New Hampshire Tuesday morning. "That future will be shaped more by what happens on Nov. 8 in voting booths across our nation than by any other event in the world."

"I have come here to make it as clear as possible as to why I am endorsing Hillary Clinton and why she must become our next president," Sanders added.