Answer:
They generally occur at the time when groups of voters begin to change their views on traditional patterns of party loyalty.
Step-by-step explanation:
Critical elections is a term used in politics to show a feedback, a change in the party ideology of a group of people who are usually party leaders or politicians. This ideological change refers to the changes of opinions on some concepts defended by the party that a certain politician is part of, generating a disagreement with between the politician and those concepts.
This change of opinion results in an intense change in the political structure of a region.
In summary, we can say that critical elections occur when they usually occur at the time when groups of voters begin to change their views on traditional patterns of party loyalty.