Saturday is decision day for House Republicans. A week ago, they sent a continuing resolution to the Senate that included a provision to defund Obamacare. Now, they've received the resolution back, minus the Obamacare provision. So what do they do? Do they attach some new measure to the resolution and send it back to the Senate -- with the hours ticking away before a possible government shutdown? Or do they drop efforts to defund, delay, or amend Obamacare and simply pass the "clean" continuing resolution before them?

When asked whether the House would pass the "clean" resolution -- a path rejected by the most conservative House Republicans -- Speaker John Boehner has said, "I don't see that happening." But there is a possibility Boehner will end up doing just that. Here is the situation he faces.

There is a lot of fear of a shutdown. The further we try to push the leadership, if they don't think that's realistic, it makes them more likely to do a clean CR.

The House Republicans who pushed hardest to attach a measure defunding Obamacare to the first continuing resolution now say they will accept replacing it with a measure to delay and defund Obamacare for a year. They say they will reject smaller measures, like repealing Obamacare's medical device tax or the Vitter Amendment, which forces Congress to purchase health coverage on the Obamacare exchanges without special subsidies. Those are worthy goals, the conservatives say, but apply to relatively small groups of people, while the conservatives are trying to spare millions of Americans from the mandates and burdens of Obamacare.

House members in the conservative faction say they have about 80 votes to support their position. But there are 233 Republicans in the House. What about the other 153? It could be that most of them would like to see some sort of Obamacare measure attached to the new continuing resolution -- either the one-year delay/defund measure or one of the smaller proposals -- but they are more concerned about the possibility of a government shutdown. "I definitely don't want a clean CR," says a House conservative. "But you very well could have a majority of our conference who say, 'Look, let's just get the CR off the table.' There is a lot of fear of a shutdown. The further we try to push the leadership, if they don't think that's realistic, it makes them more likely to do a clean CR."

So does Boehner go with the 80, or with the 150? If in fact there are anywhere near 150 Republican votes to (reluctantly) go ahead with a "clean" CR, then Boehner would have the support of the majority of the majority in choosing that path. He would also guarantee a lot of Democratic support, plus passage in the Senate -- and no government shutdown.

If Boehner chooses the one-year delay/defund route, he'll have the support of the 80 House conservatives, and perhaps the rest of the House GOP conference will go along. But he'll have the support of a small minority of House Democrats, plus the virtual guarantee of failure in the Senate -- and a likely shutdown.

If Boehner chooses the smaller measures, the medical device tax repeal, the Vitter Amendment, or both, he will likely have the support of a majority of the House GOP conference and some House Democrats. Prospects in the Senate are not clear; a majority of Democrats supports repeal of the medical device tax, but Senate Majority Leader Harry Reid has said he will not accept its inclusion in the CR. What would happen with the Vitter Amendment is not clear either, but in the past Reid has fought like a tiger to prevent any vote on it. Given that, and with time passing, the smaller-measure route carries the real danger of a shutdown.

That leaves the clean CR. It would work, it could be done quickly, and it might well have the support of the majority of the House Republican conference, not to mention Democrats. But it would certainly set off a revolt among House conservatives, probably including threats to Boehner's speakership. That is Boehner's choice on Saturday.