The agreement was between all four effected State Party Chairs and the Candidates.
There is no logic behind the assertion that since only the South Carolina vote still is pending that only the approval of the South Carolina State Democratic Party Chair was needed to nullify the terms of the pledge made by all the candidates. Consider this:
"On Thursday, Florida State Senator Ted Deutch sent a letter to the Democratic Party Chairs of Iowa, New Hampshire, Nevada and South Carolina. The letter asks the Chairs of the four early states to release the Democratic candidates from their pledge not to campaign in Florida before February 5th. Florida's primary is scheduled for January 29th, 3 days after the last of the four early primaries in South Carolina on the 26th. Senator Deutch's letter states:
On January 26th when the polls close in South Carolina, the goals you established in September when you asked the candidates to sign the Pledge will have been fully satisfied, and there will be no compelling reason for you to ask the candidates to continue to abide by the Pledge.
For five months, the candidates will have concentrated their attention on your four states. Allow Florida to have two days."
http://fl-kossacks.blogspot.com/2008/01/will-florida-no-campaign-pledge-lifted.htmlNote that even this request for flexibility coming from a Florida State elected Democrat only calls for flexibility regarding the pledge AFTER South Carolina votes, not before then. And it is directed to ALL FOUR State Party Chairs, not just to the Chair of South Carolina.
There is a reason why it is a bogus argument that only South Carolina's position now is relevant because only South Carolina has not yet voted, and I mean a reason beyond the obvious one that the agreement on it's face does not drop State's from having a say in the pledge's terms once voters in that particular state have already voted. The point of the agreement in the first place was to make sure that States like Florida IN THE FUTURE do not attempt to arbitrarily move their primary dates up to usurp the traditional focus on the first states to caucus and vote, by forcing candidates to divert their energies to campaigning elsewhere as other larger states crowd the front end of the primary calender.
All parties to that agreement agreed on terms that they felt put sufficient teeth into the agreement to stop other states from doing what Florida did this year in the future. Those teeth were designed to include a severe disincentive for candidates to campaign inside of Florida until AFTER ALL FOUR early DNC sectioned contests were concluded. Those agreements furthermore were timed to expire AFTER the literal Florida vote, not before then; not even three days before then, which is why the letter from Florida Senator Deutch REQUESTED a voluntary release that would allow candidates to campaign inside Florida AFTER the South Carolina vote.
Senator Obama and the State Chair of the South Carolina Democratic Party did not by themselves have standing to dissolve on their own an agreement arrived at by all the candidates and all four of the four effected State Chairs.