The phrase "to fail any candidate" means to judge or determine that a person did not meet the required criteria or expectations in a test, examination, or selection process, resulting in their unsuccessful outcome. Full definition
Sean Haughey TD was selected as the Fianna Fail candidate for the Dublin Bay North constituency at a selection convention ion 5th October 2017. (adriankavanaghelections.org)
Deputy Jim O'Callaghan was selected as the Fianna Fail candidate for the Dublin Bay South constituency at a selection convention in late July 2017. (adriankavanaghelections.org)
Looks like two - time failed candidate Mitt Romney is going to be telling Republicans how to get elected. (fortune.com)