It's easy to promise controversial things that require Congressional action and cannot pass Congress. The President -no matter who they are or what Congressional action they promised- can't even push their allies in Congress to do something that can't work because of the filibuster or lack of sufficient majorities. Every candidate, and every President, promises things that they know Congress won't likely deliver -- cheap talk. But there are things they can do and so promises they can keep, so long as either they are sufficiently popular or do not require Congressional action.