Graph by Sarah Binder based on House floor roll call votes.

All eyes are on Speaker John Boehner this weekend as the House GOP conference struggles to respond to the “clean” Continuing Resolution passed today by the Senate.  Stripped clean of language to defund Obamacare, the fate of the spending bill to temporarily fund the government rests in the GOP leadership’s hands.  Do they try to amend the clean CR with just GOP votes, surely risking a government shutdown early next week?  Or does the speaker dare not risk his party being blamed for an unpopular shutdown, and likely split up his red conference by calling for a vote on the clean CR?

A little House arithmetic makes plain Boehner’s predicament within his 232-member conference.  He might not be able to muster 217 GOP votes for amending the CR, and he can’t pass a clean CR without turning to Democrats for help.  To illustrate Boehner’s situation, I’ve devised a simple index of voting behavior within the House GOP conference, summing up lawmakers’ choices on pivotal votes in the 113th Congress.   The chart above shows the number of lawmakers in each category, moving from the most loyal to Boehner on the left to his the greatest thorns in his side on the right.  I tally votes against electing Boehner as speaker, against funding for Hurricane Sandy relief, against Violence Against Women Act, against the debt limit deal last March, and against the farm bill in June. Finally, I score whether the member signed the Rep. Mark Meadows (R-N.C.) letter pushing the leadership to defund Obamacare in the CR.  (Note: These votes differ slightly from those selected by The Fix in July; The Fix included two votes on the farm bill and the 112th Congress fiscal cliff vote, and did not include the Meadows letter.)

The chart above clarifies Boehner’s challenge:

First, Boehner’s go-to crowd represents a very small portion of the conference, under 15 percent of his colleagues stuck with him through thick and thin this year.  Even if we add in his colleagues who defected just once from the leadership’s preferred position, his supporters are still relatively few, making up just over a third of the chamber.  That’s a thin reed to lean on if Boehner plays Moses and takes a path that divides his red sea. (Ouch.)

Second, if Boehner relied on a strict reading of the “Hastert Rule,” he would still find it challenging to corral a majority of the majority party to support a clean CR.  To secure the votes of a party majority, Boehner must dig deep into the ranks of his colleagues who were willing to defy him twice on the most salient (and arguably consequential) votes of the year.

Finally, and possibly better news for the speaker, the right side of the chart reminds us how few GOP lawmakers have bucked the speaker at every turn.  Less than 10 percent of the conference has routinely attempted to foil the leadership’s agenda.  However, the speaker’s acute problem is that those 19 colleagues exceed the party’s margin over House Democrats.  If the speaker brings an amended CR to the floor, no Democrat will vote for the bill.  That route would likely precipitate a government shutdown.  But if the amended bill doesn’t meet the (increasingly implacable) demands of the far right of the conference, Boehner won’t get the 217 votes he needs to pass a bill without the Democrats.  That route also likely leads to a shutdown.   We’re not yet at the proverbial 11th hour before the government runs out of money.  But unless Boehner is willing to pass a clean CR with Democratic votes, it seems likely that the 12th hour brings a shutdown.