WASHINGTON (Reuters) -As U.S. farmers enter autumn harvest season worried that low crop prices and a trade war could hurt their livelihoods, Republican farm-state lawmakers are urging President Donald Trump's administration to issue economic aid for farmers by year's end. Discussions between lawmakers and the administration highlight the trade-offs Republicans face between loyalty to the president and representing constituents who have contacted their offices and flocked to town halls in their districts, worried about the impact of Trump's trade policies.