Donald Trump slammed Mitt Romney as a “fool” Wednesday for pressuring him to release his tax returns.

“We have good reason to believe that there’s a bombshell in Donald Trump’s taxes,” Romney, the losing 2012 Republican presidential nominee, told Fox News.

“Either he’s not anywhere near as wealthy as he says he is, or he hasn’t been paying taxes we would expect him to pay, or perhaps he hasn’t been giving money to vets or to the disabled like he’s been telling us he’s been doing,” he added.

Trump, who often boasts about his wealth, unloaded on Romney on Twitter: “Mitt Romney, who totally blew an election that should have been won and whose tax returns made him look like a fool, is now playing tough guy.”

He then retweeted a line from a supporter that said: “Oh, great @MittRomney is doing @SenatorReid on @realDonald Trump like losing the presidency wasn’t enough.”

Nevada’s Harry Reid, the Senate Democratic leader, had accused Romney of not paying taxes for years. Romney came under fire in 2012 when his tax returns showed he paid just 14 percent of his income in taxes.