I don't know how it was "canceled" when it was never "scheduled." Obama agreed to one date, Hillary agreed to another date, and apparently they never settled on a mutually agreeable date.
update...... No Presidential Debate for N.C. WRAL Election 2008 logo Posted: 12 minutes ago Raleigh, N.C. — A proposed debate in Raleigh between Democratic presidential candidates Barack Obama and Hillary Clinton has been called off, officials said Monday. CBS had agreed to host a debate next Sunday at the RBC Center and televise the event nationally. Clinton agreed to the date, but Obama, who had earlier committed to an April 19 debate, said repeatedly he wasn't sure whether he could fit an April 27 debate into his campaign schedule. The North Carolina Democratic Party said in a statement Monday that the logistics of staging a national event on short notice, if Obama were to agree to the debate this week, were too daunting to try to pull everything together. Democratic officials also said there were "growing concerns about what another debate would do to party unity." Clinton and Obama have agreed to attend the state's annual Jefferson-Jackson Dinner on May 2 in Raleigh. The dinner will be four days before North Carolina's May 6 primary, which is seen as critical in the tight race for the Democratic nomination. i had heard that they finally decided and agreed on this date...but i guess that information was false.
After the panning he took from the pundits after last week's debate, may very well be a case of the candidate with the commanding lead in the polls (here in North Carolina) doesn't want to expose himself to a challenger who needs help here in North Carolina. Sorta like how Bev Purdue rarely shows up for televised debates with Richard Moore. Of course polls show that race tightening to the point now that Perdue may have to reconsider.