Complex sentence: An amendment proposed by Sen. Jeff Merkley sought, unsuccessfully, to overturn the provision, which he said "allows the unrestricted sale and planting of genetically modified seeds that could be harmful to farmers, the environment and human health".
Split into simpler sentences: An amendment proposed by Sen. Jeff Merkley sought, unsuccessfully, to overturn the provision. Merkley's reasoning was that it "allows the unrestricted sale and planting of genetically modified seeds that could be harmful to farmers, the environment and human health".