Pittsburgh's most storied steel company, U.S. Steel, is on the cusp of being bought by Japanese steelmaker Nippon Steel Corp. in a deal that's kicking up an election year political maelstrom. The sale comes during a presidential campaign and renewed political support for rebuilding America’s manufacturing sector. With the United Steelworkers against the deal, Democratic President Joe Biden has all but vowed to block it. Republican ex-President Donald Trump has said he'd block it “instantaneously.” The sale has drawn opposition from Democratic and Republican senators in a rare flurry of bipartisan unity. Nippon Steel has scheduled the deal to close this year and has promised to move its U.S. headquarters to Pittsburgh from Houston.