Marshfield’s town election in April has been moved back three days so it will be held simultaneously with the primary election for the US Senate seat formerly held by John Kerry. The primary and town ballot will be held Tuesday, April 30. Town Clerk Patricia Picco said the state primary requires longer polling hours than a local election, so polls will be open from 7 a.m. to 8 p.m. The Board of Selectmen approved the change last Monday, she said. The general election for the US Senate seat takes place June 25.