The New Jersey governor went on to bluntly dismiss Buffett.

“He should just write a check and shut up,” Christie said. “Really, and just contribute. The fact of the matter is that I’m tired of hearing about it. If he wants to give the government more money, he’s got the ability to write a check — go ahead and write it.”

Monday, Buffett said Christie's comments were not "eloquent" and largely parroted a similar call from Senate Minority Leader Mitch McConnellAddison (Mitch) Mitchell McConnellGOP strategist donates to Alabama Democrat McConnell names Senate GOP tax conferees Brent Budowsky: A plea to Alabama voters MORE (R-Ky.).

“It’s sort of astounding to me that somebody that has the responsibility for being the minority leader in the Senate would think that you attack a $1.2 trillion or so deficit by asking for voluntary contributions,” Buffett said.

Last month, Buffett said he would match any contributions congressional Republicans made to the U.S. Treasury — and triple any donations made by McConnell personally.

"I offered to triple his. But that’s a sideshow. The real problem we have is we’re taking in too little money and we’re spending too much. And that’s not going to be solved by voluntary contributions," Buffett said on CNBC.

Buffett has become an increasingly prominent figure in the debate over tax reform after embracing a proposal, championed by President Obama, that would require those who make more than $1 million a year to pay an effective tax rate of at least 30 percent. The so-called "Buffett Rule" has become a cornerstone of the president's economic proposals.

The billionaire investor's secretary — Debbie Bosanek — attended the State of the Union and sat in the first lady's box in January. Bosanek has become a symbol of the debate, paying a higher effective rate than Buffett because her income comes from salary rather than investment profit, which is taxed at 15 percent.