All week long, we've been playing a big waiting game on what is going to happen to President Joe Biden's domestic economic agenda in Congress. His promised "Build Back Better" plan initially had three parts. First, there was the immediate relief needed for the ongoing COVID-19 pandemic. Next, physical infrastructure projects. And finally, human infrastructure investments. The pandemic relief passed soon after Biden took office (back when most Americans hadn't even had the opportunity to get their first vaccine shot). The other two remain undone. The negotiations to get both of them on Biden's desk for his signature are what we've all been seeing play out -- not just this week, but for the past three or four months. We're (hopefully, at least) now in the endgame of the waiting game, to mix a few metaphors with abandon.

Biden had his own metaphor he would use to describe his tripartite legislative strategy. He called it a "three-legged stool." This is a useful image, since if you take any one of those three legs away, the stool does not stand. It collapses. That is precisely how Biden has seen this effort from the beginning.

This is what drove the linkage between the two bills under consideration now -- what House Speaker Nancy Pelosi started calling a "two-track" effort. A few Democrats in the Senate demanded enough time to put together a bipartisan infrastructure bill which could pass the Senate with at least 10 Republican votes. After an enormous amount of delay, they finally conjured up this Washington unicorn, and the bill easily passed the Senate and now sits in the House.

But this bill was roughly only one-fourth of what Biden had asked for (from this particular legislative stool-leg). So the third leg -- the one which will pass using budget reconciliation rules in the Senate to avoid a filibuster -- had to expand to absorb some of what Republicans wouldn't agree to. At the same time, progressives had to make a massive compromise, down from their original $6 trillion target to only $3.5 trillion. The precursor bill with this price tag on it passed the Senate.

In the House, however, it stalled. The moderates held this bill (which would just allow both houses of Congress to begin work on the final bill, mind you) hostage. They swore they wouldn't vote for it until Pelosi brought the Senate's bipartisan bill to the floor for a vote. Pelosi finally talked them off this ledge and got them to agree to a later date, at the end of the month, to allow the reconciliation bill some time to get drafted.

Congress didn't make the due date, which was originally this Monday. The House made a lot of progress towards that goal, but the Senate is stuck in quicksand and is nowhere near as far along as the House. So Pelosi punted, promising a vote by tomorrow. The moderates accepted this short delay.

Senators Joe Manchin and Kyrsten Sinema are completely to blame for gumming up the two-track process. It's almost as if they don't want the reconciliation bill to pass, they just want the bipartisan bill they hammered out to make it to Biden's desk. That's a harsh assessment, but it is exactly what the progressives have been fearing all along -- and the entire point of Pelosi's two-track strategy (and even Biden's three-legged stool metaphor).

Sinema and Manchin have been meeting at the White House with the president and his advisors for days now. These meetings will continue (the meetings themselves are the heart of the waiting game). But currently, neither Manchin nor Sinema has even bothered to make a counteroffer -- they say $3.5 trillion is too much, but they are refusing to say what number they would accept. Sinema, in particular, seems to be completely and solely grandstanding. There was one report she was against raising any taxes on high-income Americans and giant corporations. If this is so, then she is essentially demanding either that the bill completely die or that it all be nothing but deficit spending -- unpaid additions to the national debt. Sinema also is now saying that she won't even negotiate until the House passes the bipartisan bill.

Again: this is the entire point of the two-track strategy, because this is exactly what the progressives have been fearing all along.

With the vote scheduled for tomorrow, it now seems like there are only four possible outcomes. These are (briefly):

Progressives vote no, bill fails (for now)

The progressives are adamant. If the vote is called with no progress on the reconciliation bill, around 60 of them will vote "Nay" on the bipartisan bill. Since Pelosi can only lose three votes, this would tank the bill. Pelosi said last weekend that she wouldn't put a bill on the floor if it didn't have the votes to pass, but she may reconsider. Having the bill fail once (it wouldn't be dead forever, they can bring it back up again for another vote later) might just be necessary to teach the "centrists" that the progressives are not fooling around.

Currently, the House "centrists" have been publicly stating that they simply could not conceive of the progressives doing exactly what they've been promising to do for months -- surely they'll just betray their principles and do what the "centrists" want them to do, right? This is "magical thinking" and so Pelosi might just force a failure so it can sink in that it is indeed possible.

This might also light a fire under Sinema and Manchin. Proof that their pet bill is not going to pass without a reconciliation bill might just provide enough motivation for them to start bargaining with a lot more good faith.

Progressives vote no, GOP surprises everyone by voting for it

This is a possibility that nobody's talking about, but at this point anything is really possible. It's the same scenario as above, except that Kevin McCarthy plays three-dimensional chess and surprises everyone by providing 100 Republican "Aye" votes. This would push the bill over the finish line without the progressives' help.

This sounds rather counterintuitive (if not downright insane), so allow me to explain what the reasoning would be. McCarthy (and the rest of the Republican Party) might just see passing this bill as a good thing. That's counterintuitive because it would be handing a Democratic president a big legislative victory, but consider what else it would do. It would also yank the rug out from under the entire progressive wing of the Democratic Party in a big way. Republicans really don't want the reconciliation bill to pass at all. They've been quite open about this, in fact. By helping pass the bipartisan bill, they'd be removing all leverage over Sinema and Manchin, which would put the progressives totally and completely at their whim for what goes into this bill. Which Republicans would then count as a gigantic win for their side.

It could even provide amusement for Republicans over in the House, as well. If, during the roll call of votes, it became apparent what the Republicans were doing, then Pelosi could hold the vote open until she convinces enough Democrats to switch their votes to "Nay" to tank the bill. But this would require her to frantically whip members of her own party against the bill. This would be beyond embarrassing both for Pelosi herself and for the Democratic Party at large. So there is indeed more than one reason for McCarthy to attempt this gambit.

Manchin and Sinema reach agreement, progressives vote to pass bill

We could actually have a breakthrough, either late tonight or at the last possible moment tomorrow. Senators Sinema and Manchin could finally agree to get on board with a framework for a final reconciliation bill. They'd have to agree what programs would be included in such a bill, and how much the overall bill will spend. Short of that, the House progressives are just not going to be convinced. They'd also have to go public in a big way with their acceptance of the deal -- either by signing something that's as binding as can be, or by getting in front of a few television microphones and agreeing to the whole deal.

If such a breakthrough happens -- and if it is binding enough to convince progressives -- then the vote could be held tomorrow and the bipartisan infrastructure bill would pass the House. One possible footnote to this is that just because the House passes a bill doesn't mean Nancy Pelosi has to send it up to the White House right away. She may sit on it until the reconciliation bill passes, as further insurance against any of the "centrists" going back on their word.

Pelosi punts

Or, finally, Pelosi could just punt. She could move the vote scheduled for tomorrow back another few days -- likely into next week, to allow the weekend for negotiations to continue. Perhaps Tuesday? If this does happen, it'll probably be a pretty short punt, just like the last one.

Figuring the odds

So what are the odds on these four possible outcomes? I have no real idea, just gut feelings, honestly. But I will at least share them with you and put some solid numbers to them.

The first option, the bill gets voted down with the progressives voting against it, I'd put the chances at 1-in-5. That seems about right. Pelosi obviously doesn't want this outcome, because she knows full well the beating she and her party will receive in the press immediately afterwards (which would mercilessly continue, right up until both bills actually do pass). All the "Democrats In Disarray" headlines will be dusted off once more, to put this another way. And even if they managed to eventually pass both bills, until that time comes this will just be a huge black eye for the party and will likely drive Biden's approval ratings even lower. But it might just be necessary to convince the "centrists" how serious the progressives are. So: 20 percent chance.

The second option I'd only put at 1-in-20. Even that is probably too high. Kevin McCarthy is just not that smart, in my opinion. This would totally put a cat among the pigeons for the Democrats, but it's a little too subtle for today's Republican Party to accept. That's my best guess, at any rate. I just have a rather large problem imagining McCarthy sitting down for a game of 3-D chess with Mr. Spock, that's all. Which is why I say: 5 percent (and that's being generous).

The third option would obviously be the best outcome. Nail Manchin and Sinema down, get an iron-clad promise to pass the reconciliation bill (at whatever levels they can agree to), so progressives in the House will feel confident enough to pass the bipartisan bill. But I'd still only put the chances of this happening at 1-in-10. I say this mostly because I don't think Manchin is done with his obstructionist tactics. He loves blowing through deadlines, mostly because it puts all of the inside-the-Beltway focus on him. He gets to do another full round of the Sunday morning chat shows, he gets everyone begging him for clarity, and he gets to seem all "Mavericky" to the voters back home in one of the reddest states in the entire country. Because Manchin (and to a lesser degree, Sinema) loves this attention so much, somehow I don't think either one of them is quite done. So: 10 percent.

This leaves the final option at a whopping 65 percent chance of happening. I think that's pretty reasonable and realistic, personally. In fact, my first instinct was to make that number even higher. My main reason is it has already happened once. Any deadline which has already slipped is quite likely to slip a few more times before we're done. That's just the nature of the beast, really.

-- Chris Weigant

Follow Chris on Twitter: @ChrisWeigant