Democratic Sens. Sherrod Brown and Elizabeth Warren have written a letter to the London Metal Exchange urging the firm to improve upon its proposal to reduce delays within its warehouse network. LME proposed regulations in July to reduce delays in the removal of metal in its warehouses after buyers complained that long waits kept prices artificially high for some industrial metals. "To ensure a timely resolution to market participants' ongoing concerns and to avoid further regulatory or Congressional intervention, we highly recommend that you chart a new direction for LME practices," the senators wrote. LME declined to comment.