This is the best tl;dr I could make, original reduced by 83%. (I’m a bot)
That letter cites Brazilian news articles that report US Ambassador to Brazil Todd Chapman pressured members of Brazilian President Jair Bolsonaro’s administration to lower ethanol tariffs in order to support President Donald Trump’s reelection efforts.
In the letter, Foreign Affairs Committee chairman Rep. Eliot Engel demands Chapman explain an article in which the ambassador is said to have asked for the tariffs to be lowered as a “Favor” from the Brazilian government to the Trump reelection campaign.
It isn’t clear whether Trump was involved in Chapman’s reported pressure campaign about ethanol, but as Vox’s Zack Beauchamp wrote during 2019’s impeachment hearings, the testimony of another of Trump’s ambassadors – former US Ambassador to the European Union Gordon Sondland – showed a willingness on Trump’s part “To use US foreign policy as a tool to cement his own hold on power.”