The Washington Post has reported that US President Joe Biden may delay his decision about whether to block Japanese steelmaker Nippon Steel's bid to acquire US Steel.

The report published Friday quotes sources who say White House officials are signaling that any decision is unlikely to be made in the short-term, possibly not even until after the presidential election in November. It says their deliberations have slowed after hearing "mounting concerns over the political and economic consequences of nixing the deal."

The steelmakers agreed last December to a takeover valued at about 15 billion dollars. However, the US Committee on Foreign Investment stepped in to review the security implications. It said the deal could hurt the supply of steel needed for critical industries like transportation and infrastructure.

A spokesperson for Nippon Steel said the CEOs of both companies sent Biden a letter on Sunday. The contents have not been disclosed.

Top executives from Nippon Steel met with senior US officials on Wednesday in an attempt to salvage the deal.

Both steelmakers have revealed records of communications they had with the United Steelworkers union to show that they have tried to create the "best possible environment" for good-faith negotiations.