.Biden readying to block out Nippon Steel purchase of U.S. Steel The Washington PostU.S. Steel says it could possibly leave behind Pittsburgh if Nippon package fails as Biden intends to obstruct takeover Pittsburgh Post-GazetteBiden Expected to Block USA Steel Requisition The Nyc TimesExclusive|U.S. Steel Warns of Plant Closings if Sale Breaks Down The Wall Street JournalBiden prepped to block United States Steel purchase by Nippon Steel CNN.