U.S. Steel is under fresh pressure as an activist investor aims to shake up its leadership and block attempts to revive a high-stakes $14 billion deal with Nippon Steel. The Biden administration had previously stopped the acquisition, citing national security concerns, but the two companies are now working to breathe new life into the agreement.

The activist investor, Ancora, took a bold step on Monday, nominating nine new directors to U.S. Steel’s board. Among them is Alan Kestenbaum, the former head of Stelco Holdings, who Ancora wants to replace current U.S. Steel CEO David Burritt. Ancora is also pushing to end negotiations with Nippon Steel altogether.

Despite the turmoil, U.S. Steel is standing firm. A company spokesperson reiterated their commitment to the Nippon deal, calling it “the best deal for American steel, jobs, and communities.” The $14 billion takeover was initially agreed upon in late 2023 and received shareholder approval, but it faced strong opposition from steelworker unions and political leaders.

The deal’s troubles escalated when the Biden administration blocked it, leading U.S. Steel and Nippon to sue both the government and competitor Cleveland-Cliffs, alleging misconduct in the national security review process. Cleveland-Cliffs, which acquired Stelco last year, has hinted at preparing its own bid for U.S. Steel, though tensions between its CEO and Burritt could complicate matters.

Ancora isn’t convinced the legal battles will succeed. The firm called U.S. Steel’s litigation efforts costly and unnecessary, pointing out that even former President Trump has publicly opposed the deal. If elected to the board, Kestenbaum plans to slash spending on Wall Street advisers and focus on rebuilding relationships with the steelworkers’ union.

U.S. Steel’s stock, already down 22% over the past year, dipped another 1% on Monday as the drama unfolded. With the future of the Nippon deal still uncertain, all eyes are on how this leadership challenge will play out.