Complex sentence: Potential candidates who were thought of as serious challengers to Sinn Féin candidates were warned against seeking election in some Ulster constituencies and in Munster, though in Cork all the All-for-Ireland Party MPs stood down in favour of Sinn Féin candidates.
Split into simpler sentences: Potential candidates who were thought of as serious challengers to Sinn Féin candidates were warned against seeking election in some Ulster constituencies and in Munster. In County Cork all the All-for-Ireland Party MPs stood down voluntarily in favour of Sinn Féin candidates.