belfast former u.s. president bill clinton play central role broke peace northern ireland may travel belfast week try break months-long political impasse source close talk say northern ireland without devolve administration since collapse january raise prospect direct rule reimpose london potentially destabilize delicate political balance british province clinton due belfast monday meet party trip postpone tropical storm ophelia begin batter ireland southern coast move towards northern ireland depend weather clinton schedule receive honorary doctorate dublin city university tuesday could travel belfast late day keen help source tell reuters clinton travel belfast march speak funeral martin mcguinness urge politicians finish work start irish republican army commander become cornerstone peace process main impediment talk irish nationalists sinn fein pro-british democratic unionist party dup disagreement right irish language speakers british irish governments facilitate talk express cautious optimism region power-sharing government restore month party say still challenge address bill clinton call break northern ireland political impasse source