Question

at what point do the nominees of different parties begin campaigning against each other?
during their general campaigns
before announcing their candidacy
immediately upon running

Explanation:

In electoral systems, candidates from different parties first compete in primary elections within their own parties to secure the nomination. Once the nominees are set, they move to the general campaign phase, where they directly campaign against nominees from other opposing parties. The other options are incorrect: candidates don't campaign against other party nominees before announcing their candidacy, and upon initially running, they are typically competing in intra-party primaries, not against other party nominees.

Answer:

during their general campaigns