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Billionaire Warren Buffett may be the poster child for President Obama's tax plan, but the investment tycoon insists he is not a "card-carrying Democrat."

"I support certain Republicans," Buffet told members of Washington, D.C.'s Economic Club Tuesday night. "Actually this year I gave money to a Republican congressman."

While Buffett didn't name the recipient of his rare cross-party donation, Federal Election Commission data shows that Virginia Rep. Scott Rigell was the lucky beneficiary.

Buffett gave Rigell the maximum legal campaign donation of $2,500, although that's substantially less than the $70,000 he has given to help re-elect President Obama over the past two years.

Buffett, who was in Washington for his 65 th high school reunion, joked that having a tax named after him was not his first choice for a namesake.

President Obama dubbed his plan to institute a minimum 30 percent tax rate on millionaires the "Buffett Rule" after the billionaire lamented that his secretary paid a higher tax rate than he does.

"I couldn't get a disease named after me so I settled for a tax," Buffett joked.

While Buffett has long supported increasing the current income tax rate for the wealthy, he said Tuesday that historically speaking, "our country works" despite the ever-fluctuating tax rates.

"I've operated under all kinds of tax rates including 39.6 percent on capital gains and the country has grown under all these circumstances," Buffett said.

But with the national debt topping $15 trillion, Buffett  said "somebody has to step up" and set up a plan to raise at least $300 billion more in taxes each year and bring spending down to about 20 percent of GDP.

"Just talking about reform won't solve anything on either the expenditures side or the revenue side," Buffett said. "I mean you've got to get specific about it."

Despite the growing national debt, the looming tax fight on Capitol Hill and the still struggling economic recovery, Buffet said he was optimistic about the American economy.  After all, Buffet noted, GDP per capita is six times higher than when he was born in 1930.

"It's essential," Buffett said of his optimism. "We're not smarter than the people in 1930, we don't worker harder than the people in 1930, we just have a system that works and has been working since 1776 and will keep working."