By late yesterday, the political world seemed to be feeling optimistic about the debt ceiling again. The Gang of Six had made a lot of senators happy; President Obama seemed upbeat causing a sudden spike on Wall Street; and the House was wrapping up work on a pointless vanity project, clearing the way for real work. Maybe, folks thought, we’ll avoid that catastrophe after all.

This afternoon, that optimism is evaporating again.

On Monday, Rep. Joe Walsh, a radical GOP freshman, began circulating a letter among his House Republican colleagues drawing a line in the sand: they won’t accept the McConnell/Reid plan. Period. Full stop.

Senate Republicans figured if the letter picked up no more than 50 signatures, the Senate’s “Plan B” could pick up some Democratic support, get through the House, and offer a way out of this mess. If Walsh’s effort picked up 100 signatures, we’re all in big trouble.

Greg Sargent reports today on the Suicide Squad’s progress. The news isn’t good.

…Some eighty House Republicans have now signed a letter calling on GOP leaders not to even let the McConnell plan get to the floor for a vote, a GOP aide tells me.

As I noted here yesterday, one key metric for judging whether the McConnell plan can get through the House is a letter that Tea Party-backed Rep. Joe Walsh is distributing among colleagues. He’s hoping to amass 100 members on the letter, which would be a strong statement of opposition that would call into question whether the McConnell plan has any chance of passing.

The GOP aide tells me he’s roughly 20 signatures away from that goal. The letter with final signatories will be released tonight.

Let’s do a little arithmetic. It will take 217 votes to pass a bill in the House right now (it would ordinarily be 218, but there are a couple of vacancies). There are 240 House Republicans. If 80 GOPers refuse to even consider the McConnell/Reid compromise, Plan B would need 57 House Democrats. That’s a pretty large number for a center-right agreement that includes zero new revenue.

If Walsh succeeds and the Suicide Squad reaches the 100-signature goal, Plan B would need 77 House Democratic votes for a bill Dems really aren’t going to like.

What about the Gang of Six plan? Even if it could be crafted and passed in the Senate quickly — I suspect that’s literally not possible — a growing number of House Republican leaders are concluding it’s just not right-wing enough to pass the lower chamber.

So, where does that leave us? The House won’t pass a clean bill; it won’t pass a Grand Bargain; it won’t pass the Gang of Six proposal; and at least 80 House Republicans are prepared to try to kill the Plan B compromise.

And the clock runs out in just 13 days.

Maybe someone can talk some sense into the Suicide Squad. Maybe there will be a temporary extension (there are some whispers to that effect coming out of the White House today). Maybe President Obama will give that “Constitutional Option” a second look after all.

But at this point, if you’re not nervous, you’re not paying attention.

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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.