To be promoted to the permanent grade of major general, officers who are eligible for promotion to this rank are screened by an in-service promotion board composed of other general officers from their branch of service. This promotion board then generates a list of officers it recommends for promotion to general rank. This list is then sent to the service secretary and the Joint Chiefs of Staff for review before it can be sent to the President, through the Secretary of Defense for consideration. The President nominates officers to be promoted from this list with the advice of the Secretary of Defense, the service secretary, and if applicable, the service's chief of staff or commandant. The President may nominate any eligible officer who is not on the recommended list if it serves in the interest of the nation, but this is uncommon. The Senate must then confirm the nominee by a majority vote before the officer can be promoted. Once confirmed, the nominee is promoted to that rank on assuming a position of office that requires an officer to hold the rank. For positions of office that are reserved by statute, the President nominates an officer for appointment to fill that position. For all three of the applicable uniformed services, because the grade of major general is a permanent rank, the nominee may still be screened by an in-service promotion board to add their input on the nominee before the nomination can be sent to the Senate for approval. Since the grade of major general is permanent, the rank does not expire when the officer vacates a two-star position. Tour length varies depending on the position, by statute, and/or when the officer receives a new assignment or a promotion, but the average tour length per two-star billet is two to four years.