Staggered - Tradução em português

Olá, alguém me ajuda a entender o significado desta palavra, em negrito, neste contexto, por favor.

We elect presidents here every four years. Our legislature has a staggered election schedule. The larger House of Representatives, with 435 members, is up for election every two years, while one-third of the 100-member Senate is up every two years—meaning each Senator serves six years, but the elections are staggered evenly every two years.

OBG!