Canadian Pacific Railway terminated a plan to combine with Norfolk Southern Corp., ending the Canadian carrier’s efforts to complete the first merger among major railroads since 1999.

The U.S. Army said a Canadian Pacific Railway takeover of Norfolk Southern Corp. has the potential to harm national defense, adding opposition to the possible merger plan.

Norfolk Southern Corp. set a May 12 showdown with potential buyer Canadian Pacific Railway Ltd. by announcing that date for the annual meeting, where shareholders will say whether they want the board to negotiate a merger with the Canadian carrier.

Canadian Pacific Railway is asking U.S. regulators to rule on the proposed voting trust structure it wants to use to acquire Norfolk Southern Corp.

Canadian Pacific Railway Ltd., concerned that mounting political pressure may scuttle its proposed stock-and-cash bid for Norfolk Southern Corp., plans to change strategy to sway lawmakers and reverse the momentum.

Canadian Pacific Railway Ltd. asked the U.S. Justice Department to look into a “collective campaign” by large railroads to block its hostile stock-and-cash bid for Norfolk Southern Corp.

More than two dozen shippers and legislators expressed skepticism about the bid from Canadian Pacific Railway Ltd. to acquire Norfolk Southern Corp.

Norfolk Southern Corp. is gaining political and customer support for rejecting Canadian Pacific Railway Ltd.’s takeover bid, which could make it harder for the Canadian company and investor Bill Ackman to wage a proxy fight.

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.