TOKYO, Sept 4 (Reuters) - Japan's biggest steelmaker

Nippon Steel ( NISTF ), which is seeking to acquire U.S. Steel

, said on Wednesday if its purchase goes ahead core senior

management as well as a majority of board members at the U.S.

company would be U.S. citizens.

The announcement follows Democratic presidential candidate

Kamala Harris this week echoing President Joe Biden's concern

over the $15 billion deal, saying that U.S. Steel "should remain

American-owned and American-operated".

Nippon Steel ( NISTF ) said on Wednesday that U.S. citizens would make

up the majority of the board of directors of U.S. Steel which

will also include three independent directors who would be U.S.

citizens as well. Core senior management members would be U.S.

citizens too, the Japanese firm said.

U.S. Steel would be owned by Nippon Steel North America, a

New York-based unit of the Japanese steelmaker which has been

operating in the U.S. for over 50 years, Nippon Steel ( NISTF ) said.

To gain support from politicians and labour unions,

Nippon Steel ( NISTF ) hired former U.S. Secretary of State Mike Pompeo as

an advisor and unveiled a plan last week to invest an additional

$1.3 billion in U.S. Steel's mills.

Nippon Steel ( NISTF ) said its Vice Chairman Takahiro Mori, a key

negotiator on the deal, plans to visit the United States this

month to continue deal-related meetings but declined to specify

dates or disclose the names of those Mori is set to meet.

Both companies aim to close the deal by the end of the year

depending on regulatory approvals.