What would you have the government reduce spending on?
Everything?
Close some of the military bases we have in over 200 countries. End the ridiculous, pointless, worthless wars. Reduce the military size. Reduce non-compensation benefits to congressmen/senators and other government workers (they don't need private jets or multiple offices in multiple cities). Streamline welfare systems so that they are provided on a true need basis, and make welfare "in-kind" only (for example, WIC programs and soup kitchens). Close down/consolidate a large number of federal programs and departments. Etc. Etc.
There is a LOT of waste at the federal level of our government, and nearly everything should be cut. Literally nothing cannot be reduced without compromising the intended goal of the program.