The phrase "unsuccessful campaign" means that an effort or strategy to achieve a goal or win a competition did not accomplish what was intended or desired. In other words, it was not a successful attempt. Full definition
She is familiar with the electoral process, having run unsuccessful campaigns for the Syracuse Common Council, Onondaga County Legislature and state Senate. (syracuse.com)
Last year, he endorsed former Comptroller John Liu's unsuccessful campaign against State Senator Tony Avella. (observer.com)
And many of those on the list attacking Labour incumbents did indeed fall, from the ousted Gwyn Prosser in Dover to Jayne Innes» unsuccessful campaign in Nuneaton. (politics.co.uk)