The Daily Beast's David Frum, who's back to writing from a three-month hiatus, observes of the Republican Party's political landscape:
When I left town, things looked dark for Republican donors and the politicians who served them. The party base was rejecting their leadership on immigration reform. Their preferred 2016 nominee, Marco Rubio, looked a dead man walking. Four months later, Rubio’s presidential hopes look deader than ever. But ironically, the demise of Republican support for immigration reform may turn out to be the salvation of the GOP elite.
Suddenly, the line in the sand between radicals and leadership has ceased to be immigration and has become (again!) shutting down the government and defaulting on the debt. And on those issues, the leadership is overwhelmingly winning. The shutdown caucus is led by Ted Cruz, Rand Paul, and Marco Rubio: i.e., senators less interested in winning a fight in Congress than in impressing Iowa caucus voters. They are just as happy to lose on the shutdown issue—happier, since they don’t then have to take responsibility for their actions—provided they get enough publicity on the way down.
For what it's worth, Frum, a former speechwriter for George W. Bush, himself would be considered pro-GOP establishment.