Sen. Patty Murray's got her work cut out for her. It's been less than a month since the Washington Democrat took the top spot on the Senate Budget Committee. But in that month, House Republicans used their debt-ceiling bill to highlight the fact that Senate Democrats haven't passed a full budget resolution since 2009.

Senate Democrats have an excuse: Section 106 of the 2011 Budget Control Act said that the legislation would serve as a budget for fiscal years 2012 and 2013. But that excuse has run out -- this year's budgets will be for fiscal year 2014, and there's nothing in the Budget Control Act saying it can serve as a budget for fiscal year 2014. And so Murray needs to do something Senate Democrats haven't done in years: Get 51 votes, at least, for a full budget document.

The hard part about that isn't putting together a budget. It's getting her colleagues -- particularly vulnerable Democrats up in 2014 -- to sign on to whatever budget she develops. And so that's where she's starting.

This morning, Murray sent a memo to the Senate Democratic Caucus laying out her narrative of how the budget debate has gone so far and where it should go next. The 12-page memo, provided to Wonkblog by a Senate source, begins by recapping the deficit-reduction agreed to so far. "Over the last two years," Murray writes, "Congress worked together with the Administration to pass legislation reducing deficits by at least $2.4 trillion. These first steps took us a significant way toward our deficit reduction goals. It is very important to note, however, that the vast majority of the savings in these new laws come from spending cuts." Here's Murray's table recounting the deals:

Murray next compares that deficit reduction to Simpson-Bowles and Domenici-Rivlin, the major bipartisan deficit-reduction proposals. "These bipartisan frameworks include significant new revenue and have far more balance between spending cuts and revenue increases than the deficit reduction measures we’ve enacted to date. For instance, the President’s Fiscal Commission and the Senate’s Gang of Six each proposed roughly $4.8 trillion in deficit reduction over the 2012-2021 period, with over $2 trillion coming in the form of new revenue. Excluding the interest savings of roughly $800 billion, the two bipartisan efforts proposed a roughly 1:1 ratio of spending and revenue savings." Here's the table:

The conclusion of the memo -- underlined and written in bold -- is "Revenue Must be Included in Any Deal. Tackling our budget challenges requires both responsible spending cuts and additional revenue from those who can afford it most."

What's important about this section is that Murray lays out a very clear description of how she intends to raise the revenue: By cutting tax expenditures. "The recent agreement did little to address the skewed distribution of the benefits conferred to high-income households by tax expenditures," she writes. "The top 1% of taxpayers receives nearly 25% of the benefit from these provisions. In total, tax expenditures were estimated to cost the Treasury $1.2 trillion in forgone revenue in 2011. That is nearly equivalent to what we spent on all discretionary programs in 2011."

She also notes that Republicans have, in the very recent past, supported raising revenue by closing these expenditures. "Republicans know that our tax code is riddled with giveaways for the wealthiest Americans and biggest corporations. Speaker Boehner admitted as much late last year when he proposed to raise $800 billion for deficit reduction by closing 'special-interest loopholes and deductions.'”

Republicans, however, have moved on from that position. "The current thinking is no one on the conservative side wants to use the tax expenditures for anything other than paying for the tax reform," says Doug Holtz-Eakin, president of the conservative American Action Forum. "For those clinging to the tax reform train they want to use that money to get rates down."

Rep. Paul Ryan, Murray's counterpart on the House Budget Committee, made the same point at Wednesday Wall Street Journal breakfast. "They’ve already gotten the revenues," he said, referring to the Democrats. "And if we believe in pro-growth tax reform – which is lower rates so we’re more competitive, with a broader base so we’re not doing social engineering through the tax code as much – and that’s pro-growth, which we believe – then you have to basically stick with where you are.  Otherwise, you won’t have a good tax code."

But for now, Murray doesn't need to convince Ryan and the Republicans. She needs to convince her own colleagues. And this memo is her first real attempt to do so. You can read the full document below: