Grammatically, it's simple. It's plural or singular. How many elections are there? One or many. One election, two or more elections.
Although - having said that, elections themselves are not necessarily simple. If there was an election for one position, such as for a president, then it would be simple - an election. If, as happens in British systems, you have many electorates, each electorate could be considered to be an individual election. All those elections for all the electorates would typically be held at the same time, so you could refer to the entire process as either an election, or 'the elections'.
So - it depends somewhat on the system...