.Biden preparing to obstruct Nippon Steel purchase of united state Steel The Washington PostU.S. Steel mentions it could leave Pittsburgh if Nippon package fails as Biden organizes to obstruct takeover Pittsburgh Post-GazetteBiden Expected to Block USA Steel Requisition The New York TimesExclusive|U.S. Steel Warns of Plant Closings if Sale Falls Down The Exchange JournalBiden readied to obstruct United States Steel acquisition by Nippon Steel CNN.