According to political scientists Marty Cohen, David Karol, Hans Noel, and John Zaller, this is not an accident. What we have seen in the last 40 years is the rise of an invisible primary, in which the party establishment settles upon a favored candidate:
The invisible primary is essentially a long-running national conversation among members of each party coalition about who can best unite the party and win the next presidential election. The conversation occurs in newspapers, on Sunday morning television talk shows, among activist friends over beer, in chatter at party events, and, most recently, in the blogosphere.
How can we tell who is the winner of the invisible primary? Money, for one. The candidate who raises the most money is also the one who likely has the strongest support among the well-heeled party elite. Another strong indication is endorsements from public officials, which are an outward sign of how strongly a candidate is performing in this behind the scenes conversation.
In the last 40 years, the invisible primary has become extremely important, for two reasons. First, the cost of campaigning has increased exponentially (consider: television advertisements, campaign consultants, and get out the vote organizations). Meanwhile, the utility of public funds has decreased in the last 15 or so years; public financing imposes hard spending limits that knee-capped Bob Dole in the summer of 1996, and all serious contenders have declined public funds for the primary ever since. Thus, it is hard to imagine anybody winning the nomination having raised less than $75 million on their own.
Second, frontloading has altered the nature of the nomination battle. In 1976, Jimmy Carter could start small – with virtually no establishment support – but pile win upon win for weeks on end, so that by the time people caught on to the strength of his candidacy, nobody could stop him. That’s not the case anymore. On February 5, 2008, there were a whopping 21 Republican primaries or caucuses – just one month after Iowa. To be competitive, a candidate must either have strong name recognition (like McCain and Clinton) or competent statewide organizations already in place (like Obama) by the end of the pre-primary year. That's no little feat, and to do that they need the support of local politicians and plenty of cash. In other words: they need to win or place in the invisible primary.