washington republican party two-year run majority u.s. senate serious risk may well end nov. senior congressional aid say wednesday blame donald trump drag down-ballot republican candidates 13 days go elections several senate aid party privately warn trouble republicans things good ... senate go say one republican aide ask identify order candidly discuss turbulent outlook 2016 campaign cite opinion poll aide say republicans could lose senate seat six battleground state pennsylvania illinois wisconsin new hampshire north carolina missouri reuters/ipsos poll release wednesday conduct oct. 20 oct. 24 find 41 percent republicans expect clinton win election versus 40 percent trump sharp decline confidence last month 58 percent republicans say think party nominee would win versus 23 percent clinton republicans hold 54 senate 100 seat democrats must snatch four seat win majority provide presidential candidate hillary clinton beat trump would make clinton run mate tim kaine tie-breaking senate vote since vice president vote order break tie tuesday nonpartisan cook political report predict democrats would gain five seven seat result would leave short 60 vote need easily get things do senate would provide majority less pessimistic senate republican aide say senate control still could go either way sketch problems pennsylvania aide say senator pat toomey fight dead weight top ticket refer trump missouri say democrat jason kander try unseat senator roy blunt great candidate nationally reason hold senate donald trump aide say course volatile unpredictable year still time trend reverse democrats stress break champagne accord realclear politics toomey lead 1.8 percentage point pennsylvania blunt point strongly republican missouri senator richard burr 2.8-point lead north carolina democratic challenger still senior senate democratic aide say lot paths majority do republicans enter 2016 senate race disadvantage defend 24 seat 10 democrats democratic president barack obama still relatively popular least one two white house race state republicans currently struggle new hampshire pennsylvania nevada clinton lead trump point national poll study show pattern vote recent decades outcome senate race significant correlation win white house poll hardest-fought state point extremely close race republican incumbents back wall new hampshire republican incumbent kelly ayotte tough race democratic challenger governor maggie hassan university new hampshire political science professor dante scala say republican senators state pennsylvania face one-two punch independent voters potentially turn trump electorate lean democratic presidential election years like 2016 give overall environment tilt hassan scala say republicans may verge lose u.s. senate majority aid