Japan's Nippon Steel hopes to close its $15 billion deal to buy U.S. Steel by year-end before Republican Donald Trump retakes the White House in January, a senior executive said, as the acquisition is core to its future growth.

Nippon Steel, Japan's top steelmaker and the fourth largest globally, agreed to buy U.S. Steel in December but faced opposition from a powerful labor union as well as from Trump and U.S. President Joe Biden, among others.

Before the Nov. 5 election, which handed him victory, Trump promised to block the deal if reelected.