OMAHA, NEBRASKA: Like many Americans, Warren Buffett can write a $2,700 check to support his favorite presidential candidate. But as one of the wealthiest Americans, he can also unleash immense financial clout by giving untold millions to super PACs supporting his preferred contender in the race.

When the billionaire joins a rally Wednesday with Hillary Clinton in Omaha, Nebraska, a question humming in the background will be whether Buffett, one of the world's premier investors, will throw more of his fortune behind her candidacy than he's been comfortable spending in politics in the past.

In either case, his public appearance with Clinton is aimed at offering his stamp of approval to the Democrat's economic message of inclusive capitalism and toughness against Wall Street excess. He will also join Clinton at a private fundraiser.

The "Oracle of Omaha" has referred to Clinton as a "hero of mine" and predicted last year that she would succeed President Barack Obama, whom he also supported.

"I will bet money on it," he said. "And I don't do that easily."

Democrats say Buffett carries a rare dual appeal on Wall Street and Main Street. The investment guru's annual shareholder meeting is dubbed "Woodstock for Capitalists" and drew an overflow crowd of more than 40,000 people from around the globe in the spring.

"He's one of the few highly respected business people who average people view as one of them," said Marc Lasry, a New York hedge fund manager and Democratic donor. "He's liked by lots of different kinds of people."

Buffett supported Clinton's first Senate campaign in 2000, raised money for her presidential campaign in 2008 and later endorsed Obama and appeared at fundraisers for the president.

A donor can contribute up to $2,700 to a candidate during the primaries and again during the general election. But more can be given to candidate-friendly groups and, among those organizations, super political action committees can accept unlimited donations.

Buffett has voiced his displeasure with the growth of unlimited money in politics and the emergence of the super PACS. But he made his first donation to a super PAC last year, giving $25,000 to the pro-Clinton Ready for Hillary group, raising hopes among some Democrats that he might open his wallet again and in an even bigger way.

Clinton's campaign said the two plan to discuss their "shared belief that we need to build an economy that works for everyone, not just those at the top, and their shared commitment to tax reforms that ensure that the wealthiest Americans pay their fair share."

Left unsaid is what Buffett might do in the months ahead, as a big-dollar fundraiser, a presence with Clinton on the trail, or both.

Buffett "has tremendous credibility in the left and really reassures the left about her economic orientation," said Celinda Lake, a Democratic pollster.

Buffett also offers a "perfect juxtaposition" to Republican front-runner Donald Trump, Lake said, noting Trump's attempt to cast himself as an economic wizard with a common touch, offering helicopter rides at the Iowa State Fair last summer, for example. In Buffett, Lake said, Clinton has a "perfect validator" who has made enormous wealth but doesn't forget about those with less.

And then there's the money. At age 85, Buffett has a net worth of more than $60 billion, according to Forbes, and has said he does not support super PACs. But his check to Ready for Hillary raised questions about whether he might make an exception to his longstanding unease with unlimited money in politics.

"I support her," he told CNN in April. "I would not write a huge check. I would go out and raise money for her. I'd be delighted to do that. I would hope to do it."

He said: "I did some of that in 2008 but I just don't believe that the election should be decided by the super-rich."