Jim DeMint's decision to resign from the Senate to head the Heritage Foundation stunned the political world when he made it late last year.

Former U.S. Senator Jim DeMint

In an op-ed on the Post website now, DeMint seeks to explain himself and, in so doing, exposes a critically important point about the shifting power centers in politics.

DeMint writes:

"One lesson I learned in marketing is that, for consumers and voters, perception is reality...November’s election results and exit polls suggest that a majority of Americans agree that government does too much yet still voted for more of it. The election taught conservatives that we can no longer entrust political parties to carry our message."

As we wrote at the time, DeMint's decision to walk away from the Senate -- long considered the pinnacle of power and influence in American politics -- was, in and of itself, a potent symbol of the broader shift away from traditional political parties and toward outside interest groups.

And, DeMint's opinion piece represents a broader sentiment within the conservative movement, that its establishment leaders simply lack the ability to point a way out of the political wilderness.

The rise of taxman (or, more accurately, anti-taxman) Grover Norquist and the ongoing power of radio talker Rush Limbaugh affirm that the power center of the GOP increasingly rests outside of its elected leaders. (That shrinking of establishment power was never more evident than when Speaker John Boehner was unable to find enough votes for his "Plan B" that would have exempted all but those making $1 million or more from a tax increase.)

It's not just on the ideas side where the center of the GOP is moving.  The rise of American Crossroads/Crossroads GPS as well as Americans for Prosperity -- and a slew of other conservative-minded outside groups -- have made them the major financial players in campaigns. Unlike political party committees, which are limited in the sort of donations they can accept, these outside groups can take unlimited checks from individuals. (Democrats, too, rely on outside group spending but not nearly to the extent of Republicans. That may be due to the fact that one party controls the White House and the other doesn't but only time will tell.)

The weakening of political parties is a long-term process -- driven by the growth of the Internet and its capacity/influence as an organizing and fundraising tool. But, the fissure within the Republican party between its party leadership and its base (and those figures tied to the base) has accelerated that movement.

To be clear, political parties will always have some major role in the process. Particularly on the organizational front, there are things that parties can do that no one else can.

But, there is -- and will continue to be -- an erosion of the once-dominant role that parties played in politics. DeMint is the face of that change.