“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.
In addition to a new challenge for Trump to release his tax returns, Buffett criticized him for suggesting that "building a bunch of buildings" is a sacrifice like the one made by the families of fallen soldiers. He was referring to Trump's criticism of the Muslim American parents of an Army officer killed in Iraq in 2004.
"No member of the Buffett family has gone to Iraq or Afghanistan. No member of the Trump family has gone to Iraq or Afghanistan," Buffett said. "Donald Trump and I have sacrificed nothing.
"I ask Donald Trump: Have you no sense of decency, sir?"
Clinton's fairly unusual campaign stop in Omaha is targeting a small, but potentially important single electoral vote that is up for grabs because of 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.
"I reserved a trolley for November 8th. At 6:32, I'm going to be on it all day, I'm going to do selfies — whatever it takes," Buffett said. "My goal is to have the turnout here be the highest percentage of potential voters of any district in the country."
Clinton upped the ante, promising that if turnout is high on election day, she would return to Nebraska as president.
"I will — shortly after I become president, sometime as soon as I can arrange it — come back here and Warren and I will dance in the streets of Omaha together," Clinton said.
Plus, she added, Buffett will wear his Elvis costume.