Democrats are preparing the groundwork for investigating Trump's diesel deal, -. Axius Leading Democrats, who are slated to take strong positions next year, are demanding that major banks and ports keep all documents related to potential imports or other transactions involving Russian diesel. Investigating President Trump's dealings with Moscow will be a top priority if Democrats gain control of one or both houses of Congress. This new requirement indicates that the investigation will go beyond the White House and also extend to the management of the companies. "Any importation of Russian diesel fuel into the US raises serious legal questions and could be the subject of lawsuits as well as congressional investigations," said the new letter obtained by the newspaper. It was signed by Senators Chris Coons (D-Delaware), Elizabeth Warren (D-Massachusetts), Ron Wyden (D-Oregon) and Sheldon Whitehouse (D-Rhode Island). They are the nominees to chair the powerful Foreign Affairs, Banking, Finance and Judiciary committees, respectively, if the Democrats regain control of the Senate. Rep. Greg Meeks (D-New York), who has a chance to lead the Foreign Affairs Committee in the event of a change in control of the House, also signed on. The letter is headed by Senator Gene Shaheen (D-New Hampshire), the top Democrat on the Foreign Relations Committee, who is not running for re-election. Sen. Tom Tillis (R-NC), who is also retiring, signed on. The addresses of the letter sent on Saturday are the following Wall Street companies: J.P. Morgan, Bank of America, Citi, Wells Fargo, Goldman Sachs and Morgan Stanley. The same letter was sent to the port authorities of Houston, Beaumont and Corpus Christi (Texas), as well as New York and New Jersey.