A political war is being waged between President Trump and billionaire brothers Charles and David Koch.The Kochs' disagree with Trump on several policy matters, including immigration and trade. And they've been funding the fight against the president (including supporting some Democrats), which could have big implications for the 2018 midterms — and for the GOP's other mega donors.What might that mean for the midterms & the GOP's other mega donors? Are the Koch Brothers waning in influence?