Former GOP presidential nominee Mitt Romney said Wednesday there’s only one reason Donald Trump isn’t releasing his tax returns: there’s a “bombshell” lurking in the documents.

In an afternoon Facebook post, Romney, who released his own tax returns in 2012 after his personal finances came under scrutiny, skewered Trump’s running excuse that an ongoing audit prevents him from releasing the records.

“It is disqualifying for a modern-day presidential nominee to refuse to release tax returns to the voters, especially one who has not been subject to public scrutiny in either military or public service,” the former Massachusetts governor wrote.

Romney said tax returns provide “sole confirmation” of the candidate’s claims about charitable giving and personal wealth. He said the documents would also reveal any “hidden inappropriate associations with foreign entities, criminal organizations, or other unsavory groups,” while noting such findings aren’t likely.

He also suggested Trump release his returns for the years not currently under audit.

“Mr. Trump says he is being audited. So? There is nothing that prevents releasing tax returns that are being audited,” Romney said.

He continued: “There is only one logical explanation for Mr. Trump’s refusal to release his returns: there is a bombshell in them. Given Mr. Trump’s equanimity with other flaws in his history, we can only assume it’s a bombshell of unusual size.”

In an AP interview published Wednesday, Trump said he doesn’t plan to release his tax returns before November.

Read Romney’s full post: