Trump administration officials are telling Sen. Joni Ernst they expect to reach agreement on a trade deal with Mexico “soon, very soon.”Ernst said she has spoken to President Donald Trump, Vice President Mike Pence, the U.S. trade representative and USDA Secretary Sonny Perdue about the impact of tariffs and a trade war are having on farm commodity prices, and they have expressed optimism that progress is being made.But “you can’t take optimism to the bank,” Ernst said she told administration officials.