Yes, 2012 and 2004 have some similarities, but there are also some significant differences between the dynamics of candidate entry. I don't know that my intention was to put all that much stock into the formation of presidential exploratory committees. Rather, I came across the information and felt that it would be disingenuous for me not to include. What I think I failed to adequately discuss -- and was rightfully called on it -- was the fact that the significance of the exploratory committee is on the decline. This is the simultaneously exhilarating and frustrating thing about the study of the presidential nomination process: the metrics are always changing. They are especially onerous when it comes to campaign finance rules. And that, of course, is where the exploratory committee piece of the puzzle lies. It is a campaign finance creation.
In the aftermath of Obama shunning the federal financing system in the general election in 2008 and in the aftermath of the Supreme Court's Citizens United decision, the mile markers of campaign financing within and among campaigns have changed. To be sure the federal campaign finance system has been eroded, but the raising and distribution of funds from the political action committees of prospective presidential candidates has also changed the game.
What's been lost is that step, that mile marker that was present before, the formation of the exploratory committee. Without that step, what's lost is a concrete metric for demonstrating proximity to jumping in to the presidential nomination race. PACs still do that, but candidates can run for 2012 without actually running in 2012. Candidates can roll any and all PAC efforts into a future senate or gubernatorial or another, but actual presidential bid. [And yes, it should also be noted that candidate visits to early primary or caucus states or the hiring of staff/renting of office space there are also good indicators of this as well.]
At the end of the day, we have a pretty good idea who is running for the Republican nomination. All we're lacking are the official announcements. That said, those candidates are moving more slowly in doing that than other recent candidates. Okay, fine, but why? That's the important question. Part of it is structural. I made the argument for that yesterday. But part of it also has to do, I'd argue (and so too would our trio of commenters from yesterday), with the changing landscape of campaign finance. More specific to 2012, some of these prospective candidates probably want to see how the relationship between the president and the Republican-controlled House plays out -- for a little bit at least -- first.
Regardless, this has been a different progression to the invisible primary than anything witnessed in quite a while. It is an interesting game of "who can hold out the longest" brinksmanship.