OMAHA, Neb. – Two wealthy men, two IRS audits, two tax returns, and one date – possibly.

Warren Buffett threw down the gauntlet Monday in Omaha, challenging Donald Trump to release his tax returns “anytime, anywhere” between now and election day.

Buffett, CEO of Berkshire Hathaway and among the top 10 richest men in the world, called it “an offer I hope he can’t refuse.”

“I’ll bring my return, he’ll bring his return, we’re both under audit,” Buffett said. “You will learn a whole lot more about Donald Trump if he produces his income tax returns.”

He noted that Trump has released a financial statement in lieu of his tax returns, but Buffett said that it isn’t enough.

“As someone who’s filled out financial statements and someone who’s filled out an income tax return, I can tell ya, they are two very different animals,” Buffett said.

“He’s not afraid because of the IRS, he’s afraid because of you,” he added. “You’re only afraid if you’ve got something to be afraid about.”

Buffett spoke at a rally here, where he introduced Hillary Clinton and sharply criticized Trump.

Clinton’s fairly unusual campaign stop here is targeting a small, but potentially important single electoral vote that is up for grabs due to a quirk in election law.

Nebraska’s 2nd Congressional District, which encompasses the more liberal enclave of Omaha, can award a single electoral college vote differently from the rest of the state.

Buffett challenged the crowd to turn out to vote on election day and he even put some skin in the game, promising to personally take people to the polls on election day.

“My goal is to have the turnout here be the highest percentage of potential voters of any district in the country,” Buffett said.