This is the 1427th most frequent Polish word.
wyborczych
"Wyborczych" means "electoral" or "related to elections" in English.
As an adjective related to elections, the word 'wyborczych' modifies 'commissions', indicating they are associated with the election.
Komisje wyborcze zamknęły obwody i rozpoczęto liczenie głosów.
The electoral commissions closed the districts and began counting the votes.
Here 'wyborczych' describes 'campaigns', providing information about their relation to elections.
Kampanie wyborcze pełne są obietnic składanych przez kandydatów.
Election campaigns are full of promises made by candidates.
In this context, 'wyborczych' is part of the term describing the system related to elections.