The next month in Congress might be the most momentous period for the institution in a very long time. We are almost down to the wire on President Joe Biden's entire economic agenda. Success seems elusive, but at the same time still achievable. If everything falls perfectly into place, Congress could pass legislation that children will learn about in history class right along with L.B.J.'s Great Society and F.D.R.'s New Deal. That's how momentous the next few weeks might be.

Might be. Being Democrats, there's always a good chance they'll find a way to screw it up. Already a few of them seem almost eager to destroy the carefully-constructed plan to get everything onto Biden's desk at the same time. So there is definitely not any sort of guarantee of success.

The schedule is beyond aggressive, for such enormously complex legislation. Two days from now, the House will begin churning through the business of putting together all the disparate pieces of legislation into one final bill. The House and Senate are working hand-in-hand (at least, they're supposed to be) so that both houses will come up with a bill that will pass both houses without changes. If this works as designed, it will save a huge amount of time -- on the order of months, actually. This is good, because Democrats don't have months to waste.

To get any bill passed, however, it is going to need the votes of almost every Democrat in both houses. It'll need every single vote in the Senate, and Speaker Nancy Pelosi can only afford to lose three of her caucus and still have a majority. That is the challenge.

To achieve this, the so-called "moderates" ("conservatives" is more accurate) will have to be appeased. Nobody is sure exactly what this means. Which could be a good thing, since by leaving things vague none of the holdouts have drawn any kind of lines in the sand in terms of objecting to specific programs or proposals that they just cannot support. Instead, the objections have all been centered around the overall price tag. So far, at least. This could always change as the sausage-making progresses.

The two most prominent holdouts are Senators Joe Manchin and Kyrsten Sinema. Both have flatly stated that they cannot support a bill with a $3.5 trillion price tag. Manchin has also (rather ominously) called for a "pause" in the whole process. Neither has offered a countering figure that they could support, although I did read one rumor that they're thinking "closer to $2 trillion." If this is true, maybe they'll split the difference at $2.75 trillion? Or perhaps they'll be mollified by an offer of $2.9 trillion? No one can say.

Whatever Manchin and Sinema want, though, it behooves the rest of the Democrats (led by Bernie Sanders, who chairs the Senate budget committee) to find out whatever it is as soon as possible. If this accelerated schedule is going to work, Democrats simply don't have time to indulge Manchin's go-to tactic of drawing negotiations out as long as he thinks he can get away with. Instead, he's got to be cornered and bargained with until he can support the bill. There can be no "pause" -- or not a very long one, at any rate. Sinema needs to be convinced as well, although Manchin seems to be the more contrarian of the two. Once Sinema and Manchin do get on board with an overall price, though, it's a safe bet to say that the House "moderates" will fall into line as well.

Next Wednesday is the due date for all the committees to finalize the text of their individual portions of the budget reconciliation bill. If everyone meets this deadline, then the bill's provisions will likely be made public -- we'll all get to see which agenda items made it in, which made it in only on a temporary basis, and which got left out. This is when all Democrats can start making the full-throated case why this bill will help so many millions of American families.

There are then twelve days built into the calendar before the House needs to vote on the bill. This will hopefully give the Senate enough time to act (they've got to get the parliamentarian's ruling and then survive a marathon voting session to pass it, most likely). The final deadline in the House is the 27th of the month, when Nancy Pelosi has sworn to bring the bipartisan infrastructure bill up for a floor vote.

As I said, this is beyond aggressive. Which is why Manchin and Sinema need to be brought on board before the deadline for all the final text to be delivered. Otherwise, they'll drag out negotiations for so long the Senate won't have time to act. This is the big danger.

The House "moderates" that forced Pelosi's hand on the schedule might be talked into an extension of perhaps a few days, if the final work is already underway in the Senate. But that's about all the slack Pelosi should expect. And if the infrastructure bill comes to a vote before any deal has been reached with Manchin and Sinema, then roughly 100 House progressives are going to vote against the bill. This would tank both bills.

If Joe Manchin just wants a couple more weekends where he's the most sought-after guest on the Sunday morning political shows, then Democrats can allow that. Take some camera time, Joe, no problem. But this period simply cannot drag on for as long as it did when the infrastructure deal was hashed out. That would doom the entire effort.

What this all means is that -- whether it happens in public or in the (no longer smoke-filled) back rooms -- a deal with Manchin and Sinema is critical within the next week or so. Whether we get to hear about the details of this negotiation or not (Manchin has a tendency to go public, so this is an open question), it has to happen fast.

Joe Biden's entire domestic agenda is what is at stake. The Democratic Party's chances of winning the next two elections are also at stake. If congressional Democrats can pull off a truly momentous bit of legislating, then the party will have an excellent platform to run on: "Look at what we did!" If they can't, then they won't. It's as simple as that. This month can either go down in history as one of the most momentous months Congress has ever had, or it can go down as a crushing disappointment and defeat for the Democrats.

I remain cautiously optimistic.

-- Chris Weigant

Follow Chris on Twitter: @ChrisWeigant