US Steel (X) activist investor Ancora Holdings Group said Wednesday that it is withdrawing its nomination of board members for election at the company's upcoming annual meeting.

Ancora said the suspension of its campaign follows recent progress in Nippon Steel's planned acquisition of US Steel.

The shareholder said the companies may have had "productive conversations" with US authorities over the deal, leading stakeholders to expect regulatory approval.

The proposed transaction will see Nippon Steel acquiring US Steel for $55 per share, Ancora said.