Presumptive Republican nominee Donald Trump responded to the most recent attack from 2012 Republican nominee Mitt Romney on Saturday morning on Twitter, saying Romney calling Trump racist is untrue.

Mitt Romney had his chance to beat a failed president but he choked like a dog. Now he calls me racist-but I am least racist person there is — Donald J. Trump (@realDonaldTrump) June 11, 2016

Romney, who has criticized Trump repeatedly, did so again on Friday during an interview on CNN where he also suggested Trump is hiding something in his tax returns.

Republican National Chairman Reince Priebus also responded to Romney’s critical interview on Twitter.