Sen. Hillary Clinton's campaign just accused Sen. Barack Obama of violating the pledge to only campaign in the four sanctioned early election states with a new ad that is running on national television.

As the contest moves to the fourth of the early states, South Carolina, the Obama campaign started running this ad nationally.

The Clinton campaign responded:

Statement By The Clinton Campaign On Senator Obama's Violation Of The Early State Pledge

The Obama campaign today began airing paid television advertisements in a national cable buy that include advertising in the state of Florida. There is no question that these ads are a clear and blatant violation of the early-state pledge that Senator Obama and the other leading Democratic candidates signed last year.

The early state pledge was crystal clear in its prohibition against any kind of campaign activity (outside of fundraising) in states that do not adhere to the DNC calendar. There is no ambiguity. Among the list of prohibited activities are "electronic advertising that reaches a significant percentage of the voters in the aforementioned state." (According to Nielsen, there are 6.6 million TV households in Florida that receive CNN through either local cable systems or satellite dishes. This represents 92% of all Florida TV households.) The Obama campaign knows this, but has chosen to violate the pledge regardless.

Just last week the Obama campaign snubbed the people of Florida in a memo that stated that Florida did not matter in the nominating process. After consecutive losses in New Hampshire, Michigan and Nevada, they appear to be changing course.

Senator Obama's flagrant disregard for the pledge that he signed is disturbing and calls the integrity of the pledge into question.

The two camps argued about this issue last week when Clinton won in Michigan, where the primary is non-binding and the delegates county since the state violated party rules.

Here is my story from Sunday's paper on the results of the Nevada caucus, here are some of the back-and-forth on charges of voter intimidation from both the Obama and Clinton camps.

Also worth noting -- instead of staying in South Carolina for the week, Clinton will be campaigning around the country. Clinton, Obama and former Sen. John Edwards meet tonight at 8 in Myrtle Beach, S.C. for a debate. (I'll be back on the trail in the Palmetto State Wednesday.)

Clinton opened an office in my hometown a few minutes ago.

UPDATE, 4:40 p.m.: Obama spokesman Bill Burton writes in with the official response:

"Both national cable networks told us it would be impossible for us to run advertising nationally that excluded only Florida. For that reason we consulted with the South Carolina Democratic Party Chair Carol Fowler who told us unequivocally she did not consider this to be in violation of pledge made to the early states," he said.

-- Christina Bellantoni, national political reporter, The Washington Times