It takes time to get approval for wiretaps... it even has to be sealed by the approval of the attorney general - he listed the process in january at georgetown university (there to justify the use of wiretapping), the way he pitched the process sounded almost like it was a pain in the ass for him..thus wiretapping without warrant would be easier...
isnt it harder to get the presidents authorization then the office of the attorney general? They should make it easier to get a warrant - maybe share the delegation of authority with a judge, or allowing approval via email, fax etc. bypassing the warrant and probable cause process is bullshit, and just shows how lazy and lax the authorities are.