WHERE IS HALEY? Delta Airlines, facing Transportation Department opposition to badly needed help, is complaining about the absence of its high-priced Washington lobbyist: former Republican National Chairman Haley Barbour. Transportation Secretary Norman Mineta is against Delta's bid to join a cooperative market agreement with United Airlines and Continental Airlines. The Treasury Department has approved the deal. Barbour, one of the capital's most influential lobbyists, is busy these days in his home state of Mississippi preparing his 2003 campaign for governor. Delta executives are privately complaining that their man in Washington is AWOL.