Whatever else happens with the government shutdown battle, today was a bad day for Marco Rubio's political ambitions, because in deciding to cast his vote with Ted Cruz, Rubio not only made himself seem like Cruz's lapdog, he handed Democrats a golden line of attack to use in 2016, whether he's running for re-election to the U.S. Senate or for president.
Obviously, Rubio's goal was to appease the radical right, but he did it at the cost of voting to shut down the federal government instead of giving Obamacare a chance to work. Even if Obamacare proves to be a disaster, that's a hard vote to defend in a general election, but in the far more likely scenario that Obamacare ends up being popular, it could be the centerpiece of a campaign to portray Rubio as a dangerous extremist.
It would be like the 2004 attacks on John Kerry for not supporting the troops, except it would be an honest and accurate attack. And given Rubio's demonstrated inability to handle high pressure situations, odds are that his attempts to respond will only make things worse for him.