Moments after Vermont Sen. Bernie Sanders threw his support behind Democratic frontrunner Hillary Clinton in the presidential race, Republican rival Donald Trump was certainly not feelin' the Bern.

He quickly took to Twitter with some burns of his own.

Bernie Sanders endorsing Crooked Hillary Clinton is like Occupy Wall Street endorsing Goldman Sachs. — Donald J. Trump (@realDonaldTrump) July 12, 2016

First, the man who wrote "The Art of the Deal" accused the socialist senator of "selling out."

I am somewhat surprised that Bernie Sanders was not true to himself and his supporters. They are not happy that he is selling out! — Donald J. Trump (@realDonaldTrump) July 12, 2016

Then he offered an olive branch of sort to Sanders supporters.

To all the Bernie voters who want to stop bad trade deals & global special interests, we welcome you with open arms. People first. — Donald J. Trump (@realDonaldTrump) July 12, 2016

The Sanders supporters running the campaign's Twitter account, at least, weren't having it.