Two senior Democrats in the U.S. House of Representatives urged federal regulators on Jan. 6 to reject any acquisition bid for railroad operator Norfolk Southern Corp. by Canadian Pacific Railway Ltd.

Industry groups representing major freight customers of Norfolk Southern Corp. have asked the U.S. rail regulator to reject any bid for the railroad by Canadian Pacific Railway Ltd., according to letters viewed by Reuters.

Canadian Pacific Railway Ltd. is weighing options such as a proxy fight after Norfolk Southern Corp.’s board of directors for the third time rejected an acquisition offer as “grossly inadequate” and unlikely to pass regulatory muster.

Norfolk Southern Corp. for the third time rejected an acquisition offer from Canadian Pacific Railway Ltd., saying the latest proposal also was ” grossly inadequate” and “creates substantial regulatory risks and uncertainties that are highly unlikely to be overcome.”

Canadian Pacific Railway Ltd. enhanced its offer to acquire Norfolk Southern Corp. by at least 10% and signaled a proxy fight for the U.S. carrier would start in February if there are no talks beforehand.

Canadian Pacific Railway Ltd.’s bid to merge with Norfolk Southern Corp. has raised concerns among Democratic lawmakers from Illinois, who sent a letter to regulators urging them to consider potential negative impacts on the Chicago rail hub.

Norfolk Southern Corp. soundly rejected Canadian Pacific Railway Ltd.’s $28 billion merger proposal, labeling the offer “grossly inadequate and not in the best interests of shareholders.”

Norfolk Southern Corp. announced it would restructure its truck/rail business known as Triple Crown Services, or TCS, and cut costs by moving to convert most of that unit’s intermodal freight to container equipment.

Norfolk Southern Corp. has introduced new locomotives with lower emissions for freight yard service in the Atlanta area.

Norfolk Southern Corp. said its third-quarter profit increased 16% and revenue rose 7%.