Final answer:
Any member of Congress, whether a Senator or a Representative, can propose a bill. Other parties, including the President, may draft legislation, but they must have a member of Congress introduce it.
Step-by-step explanation:
The only members of Congress that can propose a bill are any member of Congress. This includes both senators and representatives. While anyone can draft legislation, including think tanks, advocacy groups, or even the president, these entities must rely on a member of Congress to formally introduce the bill if it is to be considered by Congress and potentially become law. This process is a crucial part of the classic legislative process. Ideas for potential legislation can come from a variety of sources, but ultimately, only bills introduced by members of Congress can move forward through the legislative process and have the chance to be enacted into law.