The Constitution provides that the Congress will begin each session on the first Monday in December. The first session of each two-year Congress therefore begins thirteen months after the congressional elections are held. The second session begins a month after the next election, and continues until March 3. Some of the members who serve during that second session might have been defeated or chosen not to run for reelection in the last election. They are known as “lame ducks,” and any session held after an election is a “lame duck session.”