2020 Democratic contenders react to President Donald Trump's Iowa visit, weigh in on tariffs

Klobuchar, who has discussed environmental issues on Iowa campaign stops in the past, criticized the president’s use of renewable fuel standard waivers, which are meant for small refineries but can be given to large oil companies.

“As President Trump comes to Iowa, his administration continues to hand out RFS waivers meant for small refineries to oil and gas giants like ExxonMobil and Chevron. President Trump’s abuse of these waivers, to say nothing of his chaotic and tweet-driven trade policy, hurts farmers while lining the pockets of Big Oil,” Klobuchar said in a news release.