Check out the official press release. Edwards explained clearly why he is signing:

"This election, more than any other, is about real change and choosing the candidate who is going to fight for that change," said Edwards. "Iowa, New Hampshire, Nevada, and South Carolina need to be first because in these states ideas count, not just money. These are places where voters get to look the candidate in the eye and measure their policies, ideas, and integrity. That’s why I am signing this pledge. This tried-and-true nominating system is the only way for voters to judge the field based on the quality of the candidate, not the depth of their war chest. "I strongly encourage my fellow candidates to support this four state pledge. The Democratic Party is the party of ideas, not money; Main Street, not Wall Street; and real people, not Washington insiders, and signing this pledge reaffirms that."

The pledge was written and sponsored by the State Democratic Parties in Iowa, New Hampshire, Nevada, and South Carolina to ensure their role in the process and put the breaks on the leapfrogging that is going on now that would inevitably lead to caucuses and primaries in 2006.

Note that the DNC has decided to strictly enforce party rules by invalidating the delegates from states that move beyond the guidelines originally set up and agreed to originally by the democratic leadership in every state.

UPDATE: Obama has also signed. And Richardson, Dodd and Biden signed yesterday. 2nd Update: Hillary has finally stated she will sign.

Also, there seems to be some confusion among some in the comments. This isn't the DNC's way of dissing other states - it is their way of enforcing the rules, and the roles of the 4 states, that all of the states previous agreed to. Its too late to play the leapfrog game.

UPDATE 3: And for on the DNC end of this check out the Wa Po opinion peice today by Donna Brazile.

Here is the pledge:

WHEREAS, over a year ago, the Democratic National Committee established a 2008 nominating calendar; WHEREAS, this calendar honors the racial, ethnic, economic and geographic diversity of our party and our country; WHEREAS, the DNC also honored the traditional role of retail politics early in the nominating process, to ensure that money alone will not determine our presidential nominee; WHEREAS, it is the desire of Presidential campaigns, the DNC, the states and the American people to bring finality, predictability and common sense to the nominating calendar. THEREFORE, I John Edwards, Democratic Candidate for President, pledge I shall not campaign or participate in any state which schedules a presidential election primary or caucus before Feb. 5, 2008, except for the states of Iowa, Nevada, New Hampshire and South Carolina, as "campaigning" is defined by the rules and regulations of the DNC. It does not include activities specifically related to raising campaign resources such as fundraising events or the hiring of fundraising staff.

and as an aside, in case you haven't seen it yet, here's video on the recent almost-endorsement of Edwards by President Carter, who came from nowhere and vaulted to become the nominee and president, after his performance in Iowa.

John Edwards - Ga. Southwestern State Univ. w/ Jimmy Carter

