stepped up security in new york and washington, d.c., as authorities investigate a possible al qaeda terror plot tied to the anniversary. desperate hours aboard air force one, circling over america, trying to find a safe place for president bush to land on 9/11. my interview with the pilot of air force one, he flew that critical mission. president obama s new jobs plan, certain to be a hot topic when the republican hopefuls gather here in tampa. for monday night s presidential debate co-hosted by cnn and the tea party express. we want to welcome our viewers in the united states and around the world. i m wolf blitzer. you re in the situation room. checkpoint searches and an urgent scramble for intelligence. america, once again, faces a terror threat. this time, authorities say they have credible and specific information about a possible al qaeda plot tied to the tenth anniversary of the 9/11 attacks. the key focus, washington and new york. our national correspondent susa