refuse to sign it into law.
Can the President ask the congress to make a law?
the congress can veto a law the president passed
Only Congress can pass laws. so if the president want a law passed he must ask Congress to pass it. He usually has some of what is called political capital that he can spend to get Congress to do what he wants, particularly if he belongs to the majority party in Congress.
What the congress has to do first is they have to get a hole lot of people to say YES to the law. They have to out vote the president.
He cannot. The president can veto the bill, returning it to Congress without his signature. Congress can override the President's veto by a two-thirds vote of both the House and the Senate. If the Congress overrides the President's veto, it becomes law even if he doesn't like it. If the President refuses to enforce the law, he is violating his Constitutional oath to ensure that the laws will be faithfully executed, which would be an impeachable offense. Congress could then "fire" the President by removing him from office.
the congress
The President
The Congress can override the veto with a 2/3 majority.
While the President can suggest legislation, the actual letter of the law (specifics) is written by Congress. If a bill is passed by Congress than the President can sign the bill into law or veto it, having another impact on law-making.
The president can convince congress to pass a bill, and the president can then sign the bill into a law.
Congress cannot veto a law. Any law must be written and passed by Congress in the first place. The president can then veto it. Congress can override the veto with a 2/3 majority. After a law is passed, the Supreme Court can strike it down if they declare the law unconstitutional.
If both houses of Congress pass the bill, it is sent to the President. If the president signs it, is becomes the law. If the President does not sign it, or actively vetoes it, it goes back to Congress. If it is passed by both houses of Congress again, it automatically becomes law, although override of a President's veto is realtively uncommon.