WASHINGTON — A sputtering Congress enveloped in an atmosphere poisoned with politics and distrust enters its final weeks of the year struggling to complete a lengthy to-do list on the budget.

The so-called deficit supercommittee is hung up over taxes, raising real doubts it will succeed in its assignment of cutting deficits by at least $1.2 trillion over the next decade.

The once all-powerful appropriators responsible for everything from funding the Pentagon to making sure the Agriculture Department has enough meat inspectors are struggling, too, victims of a tea party revolt and indifference among congressional leaders themselves.

Together, the appropriators and supercommittee are responsible for filling in the details of last summer's budget and debt ceiling agreement between President Barack Obama and Capitol Hill Republicans.

With little more than two weeks left for coming up with a plan to wring $1.2 trillion from the deficit, the supercommittee remains hung up over taxes.

Democrats proposed a 10-year, approximately $3 trillion deficit-cutting plan, which included $1.3 trillion in new tax revenues. Republicans countered with a $2.2 trillion plan without tax increases.

Without new revenues, Democrats are unwilling to cut Medicare or impose a new inflation measure to reduce annual cost-of-living increases for Social Security beneficiaries.

"We have said we are very open to painful concessions and compromises if Republicans are, as well," said Sen. Patty Murray, D-Wash., the co-chairman of the supercommittee. "But these concessions will only be made and only considered in the context of a balanced deal that doesn't just fall on the middle class and most vulnerable Americans."

Failure by the supercommittee to produce a plan would trigger automatic cuts a year from now to both domestic programs and the Pentagon's budget, a prospect that has defense hawks up in arms and already working on legislation to undo the "sequester" mechanism that would force the cuts.

A sequester would reduce the Pentagon's budget by another half-trillion dollars over the next decade. That would be in addition to a $450 billion cut as part of the summer deal between Obama and congressional Republicans.

"The results of a sequester will be a hollow military," Republican Sens. John McCain of Arizona and Lindsey Graham of South Carolina told Defense Secretary Leon Panetta in a letter.

Panetta himself has warned of "devastating" consequences if Pentagon spending is cut by the automatic sequester.

The appropriators, meanwhile, are supposed to be working on a parallel track to complete the 12 annual spending bills for funding the day-to-day activities of federal agencies this year.

A month into the 2012 budget year, not one of them has been completed. The House has passed its versions of six of the bills, the Senate has approved its versions of four. Those versions have to be merged and passed again before the president can sign or reject them.

A stopgap funding measure runs out on Nov. 18.

At a brief House-Senate negotiating meeting last week, House Appropriations Committee Chairman Hal Rogers, R-Ky., promised a speedy resolution that could get three of the 12 bills to the White House for Obama's signature before Thanksgiving. The three-bill measure will also be packaged with another stopgap funding bill funding the government into December, Rogers said.

But getting the remaining spending bills completed by year's end might not happen.

"I wouldn't be that optimistic," said Rep. Rodney Frelinghuysen, R-N.J., a veteran appropriator.

At the insistence of House Speaker John Boehner, a longtime opponent of so-called earmarks, the bills are free of such pet projects, which in the past have run the gamut from new roads and bridges, grants to local police departments and historic preservation projects.

Earmarks have been criticized for creating a "pay-to-play" culture in which lobbyists and earmark recipients funnel campaign cash to lawmakers. But they also have helped build support behind appropriations bills, even from devout conservatives. Now, rank-and-file lawmakers may be less invested in the bills.

The 12 bills add up to $1.043 trillion, the spending cap agreed to over the summer. More than 50 tea party lawmakers still back an agency spending cap that's $24 billion less than that amount. The Senate measures also contain $9.5 billion for disaster aid — as permitted by the budget pact — that would come on top of the cap.

"We said we were going to spend less money and we're really not spending much less," Rep. Jeff Flake, R-Ariz., said, referring to the $1.019 trillion budget plan passed by House Republicans in April.

"The frustration that folks back home (feel) is they don't feel we've fought enough for what we believe in," said Rep. Mick Mulvaney, R-S.C., a tea party favorite. "What I hear is that we gave up too easily on (Budget Committee Chairman Paul) Ryan's budget. We gave up too easily on the debt ceiling, and we're getting ready to give up too easily on these appropriations bills."

Lacking tea partiers' support for the bills, Boehner would have to turn to Democrats for votes to pass them. To get those votes would likely require removing GOP policy "riders" that roll back environmental regulations and side with companies in disputes with unions.

Democrats also oppose efforts by Republicans to use the spending bills to block implementation of last year's law overhauling health care and new regulations governing banks and other financial institutions.

Kowtowing to Democrats to pass the spending legislation is an unappetizing prospect for Republican leaders and appears to be the main reason six of the bills haven't come to the House floor for votes.

Republicans were largely unsuccessful earlier this year in pressing many of the same riders. They were dumped overboard by the dozen as Obama negotiated directly with Boehner in the spring on an omnibus appropriations bill for the 2011 budget year that ended Sept. 30.

The power of the presidential veto means the White House tends to hold the upper hand in negotiations on appropriations bills.

"Those will go by the wayside," predicted Sen. Tom Harkin, D-Iowa, referring to the GOP policy riders.