Its certainly been an interesting week for the GOP.
You had Jeb Bush trying to outflank Marco Rubio on the right about immigration reform.
Then you had Rand Paul drawing in the likes of Rubio and Cruz in his ridiculous stunt of trying to determine if President Obama would assassinate granny sitting at Starbucks. As BooMan points out, the Paulistas are pretty successfully outflanking the neocons in the GOP.
And now you have Rubio joining Cruz in a threat to shut down the government if the Continuing Resolution doesn't defund Obamacare.
Its clear these guys are already trying to position themselves as "leader" of the lunatic wing of the GOP for the still-distant 2016 Republican Primary. Meanwhile, House Speaker John Boehner and Senate Minority Leader Mitch McConnell are quaking in fear that the lunatics will remove them from their leadership post or mount a primary against them in 2014 respectively. So they have no choice but to follow the lunatics rather than provide any real leadership.
The way I see it, the more this kind of thing heats up, the more likely it is that any Republican with a brain (I know, few and far between) is likely to abandon ship. Those who can't see this as the fuel for why President Obama is working on developing a common sense caucus are missing the boat.