Over the past eight months, politicians have joined the opposition, with both President Biden and Donald J. Trump, the Republican nominee for president, signaling their disapproval of foreign ownership of U.S. Steel.
Union officials and Nippon Steel executives have been waiting to see what Ms. Harris’s stance would be. The United Steelworkers welcomed her statement, saying it would help safeguard national security and union jobs.
Nippon Steel said it remained confident that the merger would put U.S. Steel and the American steel industry on stronger footing. “We believe that a fair and objective regulatory review process will support this outcome,” it said.
Nippon Steel has been betting that discussions will continue past the November presidential election, after which unions would potentially have less political sway.
In the United States, the president can block certain cross-border transactions on national security grounds. The question is whether an acquisition led by Japan — a close ally of the United States — could be deemed a threat.