washington republican u.s. senator mark kirk face tough re-election fight illinois say monday senate vote whomever president barack obama nominate u.s. supreme court break party leadership another defection among republicans senator susan collins maine call hear eventual nominee political fight erupt fill court vacancy leave feb. 13 death conservative justice antonin scalia many top republicans threaten block nominee put forth democratic president obama nominee could shift court leave first time decades senate majority leader mitch mcconnell say seat remain vacant obama successor take office january voters say selection cast ballot november presidential election kirk write chicago sun-times opinion piece recognize right president choose supreme court nominee look forward obama pick one senate consider confirmation also recognize duty senator either vote support opposition nominee follow fair thorough hear along complete transparent release request information kirk add kirk hold obama old senate seat say hop president would pick nominee bridge differences nominee find common grind nominee speak act extreme kirk stance illustrate mcconnell may trouble keep senate republicans fully unite fill scalia seat senators like kirk seek re-election year state democrats competitive collins face re-election 2020 say monday senate obligation hold public hear obama nominee kind thorough process hear allow best way evaluate nominee collins tell reporters accord hill newspaper appear unlikely enough republicans would peel away mcconnell allow vote senate floor republican senator orrin hatch utah say monday mcconnell judiciary committee chairman chuck grassley decide whether hold confirmation hear feel like ought put get harsh atmosphere hatch tell reporters republican kirk break u.s. senate leaders high court seat