So far, the field has been more remarkable for who's not running than for who is. This time four years ago, with both parties' nominations wide open, some 17 candidates had taken formal steps to run for president; one had even declared his candidacy and dropped out.
This year, only two Republicans -- long-shot candidates Herman Cain, a former Godfather's Pizza executive, and Buddy Roemer, who was governor of Louisiana 20 years ago -- have gone so far as to organize presidential exploratory committees.
This isn't actually so unusual, at least among Republican presidential hopefuls. By this point in 1999, only two candidates were officially running for the GOP nomination: New Hampshire Senator Bob Smith and Pat Buchanan. George W. Bush had just formed an exploratory committee, and John McCain was still silent. Although most announcements came in mid-March -- with Lamar Alexander, Dan Quayle and Steve Forbes -- McCain wouldn't enter the race until mid-April, and Bush wouldn't begin campaigning until early June.
That said, today's GOP candidates might be waiting to announce as a way to raise money without bumping against campaign finance law. As it stands, official presidential candidates have to comply with a host of restrictions on fundraising. The Campaign Legal Center explains:
Federal law requires an individual who is “testing the waters” of a federal candidacy—i.e., spending money “for the purpose of determining whether [the] individual should become a candidate”—to pay for those activities with funds raised in compliance with the federal candidate contribution restrictions ($2,500 per individual donor, no corporate/union contributions).
By holding off on an official campaign announcement, "potential" candidates can avoid federal limits on fundraising, and raise millions through political organizations other than presidential campaign committees, including 527 organizations and various political action committees. Indeed, according to the CLC, Mitt Romney is well into the process of raising money outside of campaign finance law:
[M]itt Romney has set up PACs in Iowa, New Hampshire, South Carolina, Michigan and Alabama and is spending millions on staff and consultants focused on early caucus/primary states. Other prospective Republican candidates, as well as prospective Democratic candidates in past election cycles, have done the same thing.
In other words, the thin field of official candidates probably has more to do with strategic and financial choices than it does with any reticence toward running for president.