A President may persuade members of their own party to vote for a particular bill by B, denying campaign funds to members who oppose the bill.
The President is often thought to be the leader of whatever party they are a member of, giving them a tremendous amount of power when it comes to the raising of money as they are the top draw.
So, a President can use campaign funding as a stick and a carrot to get members of Congress to vote a particular way.
If the member in Congress is in the opposition, they are out of luck.
