Robert Costa reports that House Republicans are increasingly inclined to tie the debt limit fight to the battle over the government shutdown, in order to maximize their leverage. Interestingly, this comes as Democrats, too, are increasingly seeing melding the two fights as a way to increase their leverage, as I reported this morning.

Both sides agree the government shutdown fight looks likely to drag on so long that it will spill into the battle over the debt limit, which climaxes in mid-October. Republicans won’t allow a House vote on a “clean CR” temporarily funding the government (without Obamacare defunding) at sequester levels even though that funding level would be a victory for Republicans, and even though (or perhaps because) enough Dems would support it to enable it to pass the House. Dems continue to demand a clean CR, because if they agree to anything else, they’d be giving Republicans unilateral concessions in exchange for doing what Republicans themselves say must be done, i.e., keeping the government open.

And so, Costa reports that Paul Ryan is increasingly taking on a role as a lead strategist in mapping the GOP’s likely reliance on a strategy to wrap the showdown fight into a debt ceiling battle. But in so doing, Republicans continue to base their game plan on what might be called a “strategic ambiguity” that — paradoxically enough — is the very reason Dems must not give an inch to it.

Here’s Costa, explaining the rationale:

As one House Republican explains, the leadership has, in essence, nearly given up on the idea that Senate majority leader Harry Reid will concede anything, at least in the short term, so they’re looking at how to potentially tie the debt limit to the CR impasse to force Reid’s hand. Ryan, as budget chairman and the House’s conservative whisper, is at the center of these speculative strategy talks — he knows, in fiscal and political terms, what he wants to achieve, and what his colleagues are likely to support.

As Ryan himself recently put it, referring to the government shutdown battle:

“I think it will fold into the debt-ceiling fight. I think that’s inevitable, and preferable in my opinion. I like combining all of our leverage, which is sequester and the debt limit.”

It is the way Republicans themselves have defined the terms of the debate — specifically, what counts as “leverage” for them, and the “concessions” they want from Dems — that strongly argues for Dems not to give any ground whatsoever, no matter what.

Here’s why: We don’t even know whether Republicans are actually prepared to allow default if Democrats don’t give them what they want. John Boehner has already conceded Republicans won’t allow default because: “I’m not going to risk the full faith and credit of the federal government.” Yet Ryan claims the debt limit gives Republicans leverage, anyway. But why? If Republicans are not prepared to actually default, why should Democrats give them anything in exchange for averting it? And if they are prepared to allow default — which Boehner himself defines as placing the country’s full faith and credit in jeopardy — then how can Democrats give them anything without rewarding and legitimizing a strategy based explicitly on a deliberate threat to unleash massive economic havoc if Dems don’t give Republicans what they want?

This is the “strategic ambiguity” that Democrats cannot allow to stand. If Dems do give in to GOP debt limit demands without calling this bluff, Republicans will know that they can do this again next time while again keeping their actual intentions ambiguous. If they don’t give in, Republicans will be forced to clarify those intentions once and for all. Unfortunately, the only way to get this clarification might also require finding out that Republicans really are prepared to default. That’s awful to contemplate, but the alternative — making major concessions now only to be faced with this dilemma again later and to discover the worst at that point — is hardly a better one. Indeed, it’s arguably worse. This dynamic cannot be allowed to remain. It isn’t tenable for Democrats or for the country.

But what about Democrats? Aren’t they planning to use the debt limit as leverage, too?

Yes. But here again, the difference in how each side is using it as leverage again requires Dems not to give ground.

Republicans suggest — again, without saying so outright — that the debt limit gives them leverage because their refusal to raise it threatens a level of harm to the country that Dems will not be able to accept. They suggest (with varying degrees of candor) that because of this, Dems will make unilateral concessions to them that otherwise they wouldn’t have to make. (Remember: In agreeing to raise the debt ceiling — and enabling the U.S. to pay debts already incurred — Republicans would not be conceding anything; they agree it must happen to preserve the country’s full faith and credit.)

By contrast, Democrats say the debt limit gives them leverage in the sense that it will mean Republicans will ultimately have to drop their demand for unilateral Dem concessions. Because Republicans ultimately will not allow widespread harm to the country, goes this reasoning, they will in the end have no choice but to stop asking for a reward in exchange for averting it. Get the difference? One side is dangling the threat of widespread economic harm (again, without clarifying whether they’re actually willing to let it happen) to extract concessions from the other. The other side is evoking that awful prospect in order to rebuff efforts to use it to extract concessions from them.

I’m hardly the first to point out this basic imbalance. Jonathan Chait, Steve Benen, Brian Beutler, James Fallows, and others have all done so at length. And yet, no matter how many times it is outlined, Republicans and their sympathizers, and even some neutral commentators, refuse to acknowledge the basic dimensions of the situation. In the end, the only way to clarify it adequately may be for Dems to simply refuse to give in, no matter what the consequences.