Next month, Buffett will join the Democratic frontrunner on the campaign trail as she tries to make good on his early prediction.

Buffett, who runs investing conglomerate Berkshire Hathaway (BRK-A), will stump with Clinton in Omaha—his longtime place of residence—on Dec. 16, according to the Omaha World-Herald. (The Clinton campaign did not immediately confirm the report to Fortune.) Buffett’s appearance is an effort to rally grassroots support for Clinton in Nebraska ahead of the state’s Democratic caucuses in March. Clinton lost the 2008 primary contest there to then-candidate Barack Obama by a wide margin.

Buffett and Clinton are expected to talk about tax reform. Buffett, who’s worth an estimated $63.1 billion, has long advocated for raising taxes on the rich, often citing the fact that he pays a lower tax rate than his secretary. His so-called Buffett Rule would tax all millionaires at least 30%.