There's a traditional belief in Washington — sometimes explicit, sometimes not — that there are two kinds of bills: "must-pass bills" and "messaging bills." The terms are pretty self-explanatory. Everyone agrees on which bills are essential to the functioning of the American government, economy, or society — and those bills are separate from bills that legislators or parties use to take a stand on the issues they personally or ideologically find important.

One of the hallmarks of the past several years of extreme congressional dysfunction has been an erosion of the lines between those two categories for many — but, crucially, not all — Republicans. The new strategy: linking conservative priorities, like repealing Obamacare or blocking the president's executive actions on immigration, to bills to keep the government functioning by funding government agencies or raising the debt ceiling. Each time, they pushed the strategy to the deadline — and once, even past it, for a 16-day-long government shutdown.

It might seem that the latest standoff, over keeping the lights on at the Department of Homeland Security, is a continuation of this trend. But the stakes were much lower this time than they've been in previous fights — and much lower than they could have been, had Republican leadership not penned in conservatives last year. By setting aside DHS for a funding standoff, rather than the whole government, John Boehner and Mitch McConnell created a safe space for Republicans to lash out. The question is whether they can do it again.

"Tactical radicalism"

Jonathan Chait noticed the change in some elements of the GOP back in 2010, and labeled it "tactical radicalism." It's a derogatory-sounding term, but it gets at the important distinction within the Republican conference right now.

There's general agreement on policy goals (repealing the Affordable Care Act, blocking President Obama's executive actions on immigration). But some members (including leadership in both the House and Senate) believe that when Congress is faced with a "must-pass" bill, those policy priorities need to be shoved aside if that's what it takes to get the bill passed.

Other members, meanwhile, don't feel a need to choose between the two. They see repealing the ACA and blocking executive action on immigration as "must-pass" bills in their own right. To those Republicans, a deal in 2011 to raise the debt ceiling was unacceptable if it raised taxes, because low taxes were every bit as much a "must-pass" priority as raising the debt ceiling. They don't see adding an amendment blocking executive action to a bill to fund the Department of Homeland Security as adding a "poison pill" to the must-pass DHS funding bill; they see it as giving the best opportunity for passage to the must-pass Obama-blocking immigration bill. And they greatly resent being marginalized by their party's leadership — the heart of their power is that they're able to vote down bills that don't reflect the things they think are most important.

The strategy really came into its own in 2013, when Ted Cruz championed the idea of refusing to extend government funding past October 1 unless Democrats agreed to defund Obamacare — and managed to get the leadership of the Republican party on board, albeit grudgingly. You know the rest of the story: the government shut down for 16 days, and at the end of it Speaker Boehner passed a bill with mostly Democratic support that did not defund Obamacare. But it hasn't stopped conservatives from continuing to try the same tactic, most recently on DHS funding.

From the perspective of congressional leaders in the traditionalist camp, who believe that keeping government running should be separate from other priorities, this is a disaster. They used to have a "safe space" for the more ideological members of their party to express their differences with leadership — those members could always introduce and talk up their own bills. They would never pass, but the members would get press attention and could tell interest groups they'd tried to introduce the bill. But the wing of the Republican Party has realized there's no reason, from their perspective, to stay so limited in their tactics. So leadership needs to create new "safe spaces" with lower stakes than, say, risking default on US debt or shutting down the federal government — but do so in such a way that the wing doesn't feel it's being marginalized (even though, objectively, that would be exactly what was happening).

Was the CRomnibus a breakthrough?

When you think about it that way, the DHS shutdown fight was actually a relative success for GOP leadership. Why? Because it wasn't a government shutdown fight. Congress set up the DHS funding battle when it passed a bill in December cleanly funding the rest of the government through September, and funding DHS through the end of February. It could have made ending Obama's executive actions on immigration a condition of passing the CRomnibus in December; or it could have funded the entire government only through February, instead of just DHS. But neither of those things happened. Instead, leadership teed up a showdown over the funding of a federal department for which 85 percent of the employees would still have to report to work. It wasn't quite as insulated from real-world consequences as the "messaging bills" of the past, but it was certainly a lot safer than the alternative.

The question is whether leadership can engineer something equally clever the next time around. With the bill that passed earlier this week, DHS will be funded through October 1, like the rest of the federal government. So Congress will have to pass another spending bill — either another temporary extension of current funding levels or an actual budget. That's going to be tricky enough. But September or October is also when the United States is expected to hit the debt ceiling again — so Congress will have to pass a bill raising the debt ceiling next fall at the same time as it's debating funding the government. Oh, and a new round of across-the-board spending cuts under the sequester go into effect on October 1 — unless Congress does anything to stop or rearrange them.

That's three "must-pass" bills at once — in an era when much of the majority party simply doesn't believe in the traditional meaning of a "must-pass bill."

Republican leaders were able to defuse the last big fight, in December, by promising a smaller, controlled explosion over DHS in February. If they can do the same thing this fall, it will be significant. But providing a "safe space" for conservative members only works if conservatives don't feel they're being managed — and it's hard to see how Republican leadership will successfully redirect their attention away from the September mega-deadline.