From Politico:

With the Senate stuck over whether and how to reform the PATRIOT Act before parts of it expire within days, officials across Washington are starting to contemplate a future in which lawmakers don’t act — and key surveillance provisions simply die. If Congress doesn’t renew the law — which expires on May 31, during the Memorial Day recess — the National Security Agency won’t be able to conduct any massive new sweeps of phone records, which Senate Majority Leader Mitch McConnell and other national security hawks have said are crucial to fighting terrorist threats like ISIL. According to a grandfather clause in the PATRIOT Act, however, the NSA can continue investigations it’s already started based on the phone data.