Question

What is the most effective way for congress to prevent a presidents foreign policy?

Answer 1

Cut off budget support for that policy

Answer 2

Congress can do a number of different things to prevent or influence the Presidents foreign policy. Congress can seek to prevent funding of aspects of a President's foreign policy, Congress can demand administration officials to speak before a Congressional committee, Congress can seek to outlaw certain activities and override a presidential veto if necessary, and a multitude of other things as well.