Warren Buffett made an offer to Trump on Monday he might finally have trouble refusing: meet in Omaha or Palm Beach, any time, and show each other their tax returns.

In response to Trumps chronic response for not revealing them — he’s under audit— Buffett said that’s no excuse. “We’re both under audit,” Buffett revealed, while speaking at a rally for Hillary Clinton in Omaha. “And believe me, nobody’s going to stop us from talking about what’s on those returns.”

Donald Trump’s campaign manager Paul Manafort told “CBS This Morning” last Wednesday that the Republican Party’s presidential nominee “will not be releasing” his taxes.

Trump has previously given varying accounts about when his tax returns would be released.

In an Associated Press interview in May ,Trump said “there’s nothing to learn” from his tax returns and dismissed the idea that voters had a right to see them before going to the polls.

But, in a tweet, the self-professed billionaire said he told the news agency he would release his returns when the audit is finished, “not after [the] election.”

There is no legal requirement for a presidential candidate to make his or her tax returns public, but every major party nominee since 1976 has done so.

On social media, some pointed out that the tax returns could contain valuable information about Trump’s background.

Republican presidential nominee Mitt Romney joined those critics in a post on Facebook, calling it “disqualifying” for a nominee to a major party not to release returns. “Tax returns provide the public with its sole confirmation of the veracity of a candidate’s representations regarding charities, priorities, wealth, tax conformance and conflicts of interest.”

Romney said the fact Trump is being audited doesn’t prevent the release of those returns.

Analysts said that Trump likely pushed the envelope to turn ordinary income into capital gains, and deferred the payment of tax through like-kind exchanges. The tax returns could also verify how much income he receives from licensing his name.

Read:What Trump’s taxes could tell us about the candidate