Changes sourcing, adds background

May 9 (Reuters) - Nippon Steel 5401.T Vice Chairman Takahiro Mori is headed to Washington next week as the company seeks to win approval of its $15 billion bid for U.S. Steel X.N, a person familiar with the matter said.

Semaphor, which first reported news of the visit, said Mori would meet with Trump administration officials during the trip, citing sources.

U.S. Steel and Nippon Steel did not immediately respond to requests for comment.

Former President Joe Biden blocked the proposed tie-up in January citing unspecified national security concerns related to a national security review of the deal led by the Committee on Foreign Investment in the US.

After the decision, the two companies sued CFIUS, which scrutinizes foreign investments for national security risks, alleging that Biden had prejudiced the committee's decision and violated the companies' right to a fair review.

They argued Biden did so in 2024 by expressing opposition to the deal when he was running for re-election to win support from the United Steelworkers union in the swing state of Pennsylvania, where U.S. Steel is headquartered. The Biden administration had defended the review as essential to protecting security, infrastructure, and supply chains.

In April, President Donald Trump directed CFIUS to take a fresh look at the merger to help determine if "further action" is appropriate, raising hopes that the deal could gain an elusive green light.

But Trump has since doubled down on comments expressing opposition to the deal, saying later that month that he didn't think a foreign company should control U.S. Steel, dimming hopes for approval.

(Reporting by Alexandra Alper in Washington and Arsheeya Bajwa in Bengaluru; Editing by Shilpi Majumdar and Chizu Nomiyama)

((ArsheeyaSingh.Bajwa@thomsonreuters.com; +91 8510015800;))