It was four weeks ago when 10 senators — five Republicans and five Democrats — announced a breakthrough agreement with the White House on infrastructure. There were still details to work through, but the framework, which followed months of negotiations, was finally in place.

Or so they said.

With the basic outline of the breakthrough compromise ostensibly complete, Senate Majority Leader Chuck Schumer (D-N.Y.) scheduled a procedural vote yesterday — not on final passage of a compete piece of legislation, but to move the debate to the next stage. Democrats needed at least 10 Republican votes; they ended up with zero.

Republicans voted Wednesday to block the Senate from beginning debate on an infrastructure proposal, saying they wanted more time to finalize the details of the agreement…. The procedural motion failed 49-51, with Senate Majority Leader Chuck Schumer switching his vote to “no” at the end to preserve his option to call the same vote on another day. The motion needed 60 to succeed.

As the Senate’s official roll call shows, the parties were evenly divided, with no members breaking partisan ranks.

This leads to three questions. The first, of course, is what happens now. As NBC News’ report added, a bipartisan group of 22 senators — 10 Republicans, 11 Democrats, and one independent who caucuses with Democrats — issued a statement yesterday vowing to move forward with their negotiations on a $579 billion infrastructure package.

The group, led in large part by Sens. Kyrsten Sinema (D-Ariz.) and Rob Portman (R-Ohio) claimed in the statement that members “have made significant progress and are close to a final agreement.” Portman specifically told Democratic leaders that he believes the Senate should be able to vote on the not-yet-ready compromise on Monday.

Which leads us to the second question: Is this likely to work out? If these 22 senators reach an agreement — and there’s no guarantee that they will — it would be important, but not determinative. The package would still need 60 votes in the Senate to advance, which would offer proponents no margin for error, and it would also still need support from House Democrats.

That’s not a sure thing, either. In fact, House Speaker Nancy Pelosi (D-Calif.) told reporters this morning that her side of Capitol Hill is prepared to effectively ignore the bipartisan deal until the Senate also passes an as-yet-unwritten reconciliation package that will include more ambitious progressive priorities. That’s likely to take a while.

And that leaves Question #3: What happens if the bipartisan efforts fail? In theory, the obvious solution is to simply take the infrastructure framework, add it to a reconciliation package, and pass the whole thing with a vote that Republicans wouldn’t be able to block.

That would almost certainly be the most straightforward and effective solution, but that would also force Democrats into a no-margin-for-error legislative dynamic. If just one member of the Senate Democratic conference — say, a certain someone from West Virginia, for example — were to balk, the entire infrastructure initiative would fail catastrophically.

Watch this space.