new york koch brothers powerful conservative mega donors unite state use 400 million political arsenal try block republican front-runner donald trump path presidential nomination spokesman tell reuters wednesday decision billionaire industrialists another setback republican establishment efforts derail new york real estate mogul bid white house follow speculation kochs would soon launch trump intervention plan get involve primary say jam davis spokesman freedom partner koch brothers political umbrella group would elaborate brothers strategy would nov. election succeed democratic president barack obama three source close kochs say brothers make decision concern spend millions dollars attack trump would money waste since yet see attack trump stick koch brothers also smart millions dollars pump fail 2012 republican presidential bid newt gingrich mitt romney source say donors media report speculate since january kochs gather 500 america wealthy political donors california resort would deploy vast political network target trump kochs oppose protectionist trade rhetoric hardline view immigration include build wall along u.s. border mexico deport millions illegal immigrants many republican figure business backers eager see trump political outsider tap rise anti-establishment sentiment fail bid nomination prefer instead traditional candidate like u.s. senator marco rubio florida trump rack series win early nominate contest opponents include rubio u.s. senator ted cruz texas grow sense inevitability win party mantle edit richard valdmanis chris reese peter cooney article fund part sap independently create reuters editorial staff sap editorial involvement creation production exclusive koch brothers use fund try block trump nomination