The leaders of President Obama's deficit commission on Wednesday proposed an ambitious plan to rebalance the federal budget by slashing spending on most federal operations, curbing increases in Social Security benefits and wiping out more than $100 billion a year in tax breaks for individuals and businesses.

The proposal is aimed at cutting $4 trillion from deficits over the next decade.

The plan was drafted by the men Obama picked to lead the commission effort, former Clinton White House chief of staff Erskine Bowles and former Republican Sen. Alan Simpson. They presented the document during a closed-door meeting of the 18-member commission, which is to make recommendations by Dec. 1 for reining in record budget deficits.

Commission members, who include a dozen sitting members of Congress, emerged from the morning session in a Capitol Hill hearing room praising the seriousness of the effort but voicing deep reservations about the details.

Asked whether he could support the proposal, Sen. Judd Gregg, R-N.H., the senior Republican on the Senate Budget Committee, said no. "This is the starting point. It shows the size of the problem, which is massive," Gregg said. "This is the draft for discussion purposes to get us all thinking."

"It's a lot to absorb," added Rep. Dave Camp, R-Mich., who is in line to chair the tax-writing House Ways and Means Committee. He declined to comment further.

Some Democrats had criticisms, with Rep. Jan Schakowsky, D-Ill., flatly rejecting its calls for Social Security benefit reductions.

"It's a lot to digest. I support the goal," said Sen. Max Baucus, D-Mont., chairman of the Senate Finance Committee. But, he said, "we're at the early stages."

Senate Budget Committee Chairman Kent Conrad, D-N.D., said commission members will meet this week and again next week to continue discussions and "offer alternatives."

Rep. Paul Ryan, R-Wis., battered by Democrats over the details of his own plan to balance the budget, said he is excited to "see another plan put out there."