Answer:
It is known as crossover voting.
Step-by-step explanation:
In crossover voting, some voters decided to cast votes in the primary of the opposing party, that is, the party they are not affiliated with.
This act is usually intentionally carried out.
The intention could be to
* prevent one of the nominated candidate in the opposing party, which they dislike from winning.
* stop an opposing candidate which they see as a threat to their party from winning the primary.