What is the main lawmaking body of the legislative branch of the United States government?

The main lawmaking body of the legislative branch of the United States government is the United States Congress, which consists of two chambers:

1. The Senate: The Senate is one of the two houses of Congress. It comprises 100 senators, two from each state serving six-year terms. The Senate has specific powers, including ratifying treaties and confirming presidential appointments.
2. The House of Representatives: The House is the other chamber of Congress, consisting of 435 representatives. The number of representatives for each state is based on its population. Members serve two-year terms. The House has the power to initiate revenue-related bills.

Both the Senate and the House of Representatives play integral roles in the legislative process, including proposing, debating, amending and passing bills that, upon approval may become federal laws. The legislative process involves collaboration and negotiation between the two chambers before a bill is sent to the President for approval or veto.