If you want your newspaper to stay creditable in an election campaign, you’re expecting a lot. Creditable means deserving of praise. Who feels like praising a newspaper in the heat of an election campaign?
Credible, however, means worthy of belief, and that’s enough to make a newspaper a force in any election.
Newspaper reporters would be credulous if they believed everything the politicians told them. The word means gullible, and you don’t want to see signs of it in your newspaper.