If the U.S. economy and the full faith and credit of the nation are going to be rescued before Tuesday’s deadline, the life-preserver is almost certainly going to come from the Senate. There are multiple angles to keep an eye on today.

Senate Majority Leader Harry Reid (D-Nev.) already unveiled what appeared to be a gift to Republicans: more than $2 trillion in cuts, with no revenues at all, and an extension through the end of next year (which GOP leaders said they wanted up until a few weeks ago). Is this overly-generous offer good enough to satisfy Republicans? Apparently not.

Which leads us to today. At this point, the goal is pretty obvious: Senate Dems have to make some modifications to the Reid plan that would (a) make it palatable to enough Senate Republicans to result in a bipartisan deal that could overcome a possible filibuster; (b) be reasonable enough to prevent too many Dems in both chambers from recoiling; and (c) conservative enough to stand a chance in the House.

Oh, and Senate Dems probably have to do all of this today, with the global economy hanging in the balance. No pressure.

Getting a bill through the Senate is going to be challenging enough. If there’s a GOP filibuster, Dems would need at least seven, and almost certainly more, Republican votes to reach the 60-vote threshold. (Some in the Senate Dem caucus are likely to balk at an unbalanced deal, making the need for more Republican votes even greater.)

How feasible is this? Sen. Scott Brown (R-Mass.) appears to be on board with Reid’s compromise, so that’s one. Dems are also reportedly eyeing Sens. Snowe, Collins, Kirk, Alexander, Chambliss, Crapo, Coburn, Corker, and Murkowki as GOP possibilities. It’s worth noting, though, that Collins indicated overnight that she’s opposed to Reid’s compromise for reasons that remain unclear.

To help make the package more attractive to these GOP senators, Reid is taking his conservative offer and moving it even further to the right.

The gist: Reid hopes to entice Republicans to support his plan in two ways. First, with slightly deeper cuts. Second, by adopting an idea, first proposed by Senate Minority Leader Mitch McConnell, that would delegate the authority to raise the debt limit to President Obama — and give Congress the prerogative to attempt to block Obama from taking that action.

It does not include any penalties or triggers to force Congress to enact entitlement and tax reforms in the coming months.

As we discussed in some detail yesterday, these triggers are likely to be critical to reaching an agreement. Reid hasn’t included them yet, but that’s probably because he intends to use them in the negotiating process. This one piece of the puzzle may ultimately prove to be the make-or-break provision.

What’s more, Republican support matters for more than just cloture: the goal is to craft a bipartisan bill. Even if there’s no filibuster, if the Senate passes a bill with only Democratic support, it’s doomed to fail in the House.

Also keep in mind, Dems, at this point, aren’t exactly trying to meet the specific demands of a ransom note. Republicans aren’t saying exactly what they want changed in Reid’s offer; Reid is just moving it to the right to sweeten the pot. Presumably, today, Senate Minority Leader Mitch McConnell (R-Ky.) will have to start saying what he actually wants out of this deal.

Speaking of McConnell, there were some rumors late yesterday that the Minority Leader would only talk to President Obama going forward, and would refuse to negotiate with Reid. Those rumors turned out to be untrue, though McConnell has asked that the White House play a direct role in the process today.

And then, of course, there’s the clock. If Senate Republicans want to drag this process out, they can push a vote until Monday morning, around 7:30 a.m., leaving the House one day before Tuesday’s deadline If Senate Republicans are willing to allow an expedited process for the good of the country, the vote could come about 16 hours from now.

We don’t yet know which scenario is more likely, though the Washington Post noted that “even Sen. Jim DeMint (R-S.C.)” indicated late yesterday he would “take into account an appeal from McConnell to allow an expedited process.”

There is a light at the end of this tunnel. A sufficient number of Senate Republicans can accept Reid’s terms; the bill could pass the Senate tonight; and a bipartisan House majority could end this nightmare tomorrow or Monday.

Or Republicans will reject the compromise, the light at the end of the tunnel is a train, and on Tuesday, we’ll all be crushed.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.