Ex-White House hopeful Mike Huckabee tore into former Republican presidential nominee Mitt Romney on Thursday for insinuating that his successor, presumptive Republican nominee Donald Trump, is hiding a “bombshell of unusual size” in his unreleased tax returns.

“I supported Romney, just as I will Trump, despite having serious differences with both,” Huckabee wrote on his website. “But I am especially disappointed in Mitt for this latest attack.”