The Constitution does not specify the duties and powers of the speaker, which are instead regulated by the rules and customs of the House. Speakers have a role both as a leader of the House and the leader of their party (which need not be the majority party; theoretically, a member of the minority party could be elected as speaker with the support of a fraction of members of the majority party). Under the Presidential Succession Act (1947), the speaker is second in the line of presidential succession after the vice president.