The top Republican on the Senate aviation subcommittee, Sen. Kay Bailey Hutchison of Texas, warned that lengthy lines at airport security checkpoints are almost certain to get longer next weekend when airlines are required by law to inspect all checked baggage for explosives. The Senator said yesterday on CNN: "This is going to cause a backup at many airports... People are going to have even longer waits than we are used to now." The new aviation security law, passed in response to the September 11 terrorist attacks, requires airlines to have systems in place to inspect all checked bags for explosives by Friday. This could include sending the bags through explosive detection machines, having them inspected by hand or bomb-sniffing dogs, or making sure that no bag is loaded on a plane unless the passenger also boards. "We are trying to screen, in some way, every bag that goes on an airplane," Hutchison said. "The major vulnerability we have today is checked baggage." Federal Aviation Administration spokesman William Shumann said the agency plans to enforce the law. He said FAA special agents at airports will check to see if the bags are being inspected for explosives. "The mandate is to screen all checked bags," Shumann said. "That's what we will expect the airlines to do." The Transportation Department is expected to announce this week how airlines will meet the deadline. "That deadline indicated to the Department of Transportation that Congress wanted this done really quickly," said Sen. Charles Schumer, D-N.Y., on CNN. "People want security in their travel. That's the only thing that will bring travel up again."