It finally happened. Mitt Romney is finally being cast as “The Establishment.” Want proof? Look no further than the visceral response South Carolina Governor Nikki Haley‘s endorsement of Mitt Romney aroused.

On his radio show Friday, Rush Limbaugh explained,

You know, [Haley] wants to be veep, maybe.  I don’t know.  She wants higher office in the Republican Party.  The Republican Party is still run by the Republican Party establishment, even though they deny their existence.

… She has, obviously, [aspirations] to advance higher in the Republican Party.  Now, next time you hear anybody tell you there isn’t a Republican establishment, just look at this instance here with Nikki Haley if she wants to be vice president.

Later, Mark Levin took to the air in a more blunt fashion, saying “bye, bye Nikki.” (Video here.)

This interests me for a few reasons. First, it is clear that grassroots conservatives (and their leaders) are finally starting to officially consider Mitt Romney “The Establishment” candidate. This could be a dangerous turning point for Romney — especially considering many of these same conservative opinion leaders reluctantly endorsed Romney over John McCain in 2008.

This is a trend. The outrage over Haley’s endorsement comes on the heels of outrage over National Review’s recent editorial attacking Newt Gingrich (which many interpreted as a tacit endorsement of Romney). Ironically, though, the critics seem to be taking a page out of NR’s devious playbook. Just as NR declined to actually endorse a candidate, Limbaugh has also declined to pick a horse.

Time is dwindling. It’s fine to call Romney the “establishment” candidate, but at some point, stopping Romney will require conservatives backing one of his opponents. Presumably, this could be helped along by having a leader — such as Limbaugh — go out on a limb. Unless conservatives coalesce around someone, the anti-Romney talk is just talk…