The ranking Republican on the Senate Budget Committee warned on Monday that President Obama's budget proposal will lead to unsustainable debt levels and send the country on a fiscal path resembling that of a "banana republic."

Sen. Judd Gregg, R-N.H., and Senate Minority Leader Mitch McConnell, R-Ky., offered a grim assessment of the $3.6 trillion proposal following a report over the weekend that found the budget plan would produce $9.3 trillion in deficits over the next decade.

"The president's budget spends too much, taxes too much, and borrows too much. ... I don't think I've witnessed this level of unease about a budget certainly in the time that I've been here," McConnell said, calling the plan a "tough sell" for centrist Democrats.

"We can't afford this," Gregg said.

He called the deficit estimates attached to the budget plan "staggering," and he warned that such deficits would trigger a national debt that amounts to "running your country into the ground."

"What's being proposed here is a massive increase in taxes in order to massively increase the size of the government and have virtually no fiscal discipline on the side of borrowing," Gregg said.

The Congressional Budget Office on Friday estimated that the budget proposal would produce $9.3 trillion in deficits over the next decade — or $2.3 trillion more than the White House had estimated.

The report predicted that such deficits would double the country's public debt to 82 percent of its gross domestic product by 2019.

Gregg, who was nominated by Obama to be commerce secretary, but withdrew his name from consideration, has emerged as a top critic of the budget plan, and escalated his criticism in light of the deficit projections.

"The effect of it will be that it will pass on to our children a debt ratio which is not sustainable ... a public debt of about 80 percent of GDP, which basically is the type of debt ratio you see in banana republics," he told FOX News. "And it stays at that level for as far as the eye can see, along with deficits that are about 4 percent to 5 percent of GDP. Those aren't sustainable numbers, so we've got to take another look at this, and figure out a way to close down the gap."

White House spokesman Robert Gibbs said Friday that the new projections won't stop Obama from achieving his goals or keeping his promise to cut the country's red ink in half within four years.

The administration is a bit more optimistic about the nation's economic growth over the long term than congressional analysts, Gibbs said.

The Associated Press contributed to this report.