Republicans are warning President Donald Trump that his decision to flood supermarkets with foreign ground beef is hurting a key group in his base as the midterm elections near their climax.Voters in beef-industry-heavy states, like South Dakota, Nebraska and Kansas, supported Trump in his bid for a second term. Now, lawmakers from those states say his decision to lift tariffs on hundreds of thousands of tons of foreign beef is putting the very people who elected him in a bind.Sen. Mike Rounds, R-S.D., who is running for re-election, said his voters in South Dakota "love the president," and vi...