Sen. Marco Rubio Sen. Marco Rubio (R-Fla.) (Alex Wong/Getty Images)

Sen. Marco Rubio (R-Fla.), in the wake of his success in shepherding immigration reform through the Senate, almost immediately adopted the “defund Obamacare or shut down the government” banner.

One suspects this is a bone to the right, given that few question Rubio’s political smarts and ability to recognize this stunt is going nowhere during the Obama administration.

In Florida on Monday, Rubio held a news conference in which he defended his gambit with the same spurious argument he and others have been offering:

I don’t want the government to shut down. I want our military to function. I want our Social Security checks to go out. I think we should pass a budget that funds the government. I just don’t think it should fund Obamacare, because it’s a disaster. We shouldn’t waste a single cent more on a disaster. If it shuts down, it’s because the president chooses to do so. It’s the president who’s threatening to shut down the government. It’s the president who is saying that if we don’t fund Obamacare he wants to shut down the government. I think that’s a bad position for him to have.

Actually, it’s a great position for President Obama to have, and is the one maneuver that might secure the Senate’s Democratic majority. But interestingly, Rubio seemed to hint that he might not be all in:

Reporter: Do you think you have the votes?

Rubio: Well, I don’t know. I don’t know where we are today on it. I think we’ve got a lot more convincing to do. But look, I’m open to a better idea. If someone’s got a better idea on how to prevent Obamacare from hurting millions of Americans, I’m open to it. But right now the only one I’ve been able to identify is the debate we’re going to have in September. And the only thing I’ve said is, ‘I’m not going to vote for a short term budget that funds Obamacare.’ I’ll vote for one that doesn’t because even though I’ve traditionally not voted for short-term budgets, I’m willing to do so this time if it doesn’t fund Obamacare.

Let’s unpack that. First, he concedes he doesn’t have the votes. Then he expressly leaves open the door to an alternative. (How about winning back the Senate?) And then he allows that he’s never voted for short-term budget deals anyway (So in the words of Hillary Clinton, what difference does it make [if he votes no again]?).

Rubio’s office did not reply to my question as to whether Rubio was looking for a plan B or whether he was having second thoughts about a position as flimsy as the empty threat to shut down the government.

Frankly, there is nothing wrong with advocating an idea such as delaying Obamacare and trying to round up bipartisan support. But in this case, Rubio and the other members of the shutdown squad have chosen the one approach Democrats will never, ever agree to. It therefore becomes a stunt and not a reasoned approach to hobbling Obamacare.

One final note: Obamacare defunders keep saying the government shutdown is the best opportunity to get rid of Obamacare. That’s just wrong. The best shot before Obama leaves office will come with the roll out of the exchanges; the chance to demonstrate how entirely unworkable the legislation is will be handed to the GOP on a silver platter. But in reality, the only way to get rid of it is to win the White House and the Senate. That will require restraint and good judgment, neither of which is in great abundance among those threatening to close the government.