.Biden preparing to obstruct Nippon Steel investment of U.S. Steel The Washington PostU.S. Steel claims it could leave Pittsburgh if Nippon offer flops as Biden prepares to block out requisition Pittsburgh Post-GazetteBiden Expected to Block United State Steel Requisition The Nyc TimesExclusive|United State Steel Warns of Plant Closings if Purchase Falls Down The Commercial JournalBiden prepared to block United States Steel investment by Nippon Steel CNN.