There’s a lot of confusion over defunding Obamacare and shutting down the government. I think Karl Rove, on the DON’T DO IT side, and Bill Wilson on the STAND FIRM side both misunderstand the mechanics of shutdowns and defunding.

The background: On Sept. 30, the fiscal year ends, and so funding for government runs out, absent new appropriations bills. The planned vehicle for funding fiscal year 2014 is a “continuing resolution” — basically continuing the current year’s spending levels, and thus punting any budget fights.

If no CR passes by Oct. 1, we get a government shutdown.

Here are some things you should know about this debate:

  • Shutting down the government won’t defund Obamacare: Almost all Obamacare spending is “mandatory spending.” Obamacare authorized that spending until the end of time, and it doesn’t need to be appropriated every year. So under a government shutdown, we’d run out of discretionary spending, but most of Obamacare would keep humming.
  • A continuing resolution could defund Obamacare: Just because it’s “mandatory” doesn’t mean it’s invincible. A continuing resolution could contain a “policy rider,” as appropriations bills often do, which really does defund Obamacare.
  • Defunding Obamacare would require cooperation of the Senate and the White House: Because you’d need to pass a CR defunding Obamacare to actually defund the mandatory-spending portions of Obamacare, that would need to pass both chambers and get the White House signature. You can’t defund Obamacare without Obama.
  • Conservatives say they think Obama can be coerced into defunding Obamacare. Will Obama let his whole government go defunded just to save this one unpopular law?

I think Obama will let the government shut down rather than defund Obamacare. David Freddoso puts it well:

If you think you can get the Democratic Senate to pass (and Obama to sign) a bill that funds the government while defunding Obama’s absolute top priority without first going through a prolonged government shutdown — and we’re talking weeks or months here, not days — then you’re just not being serious. This has no chance of success unless you shut the government down for a very long time.The guy already lost the House so that he could get Obamacare — do you really think he’s going to cry uncle one week into a few embassy closures? Obama cries uncle only when tens of thousands of government employees start having their homes foreclosed because they’re not being paid.

It’s one thing to think you can gain some ground in a shutdown-showdown by haggling over levels of spending or even forcing a delay to the individual mandate or something like that. But this isn’t going to happen here, and that’s probably why there won’t be nearly enough votes to carry out this threat.