OMAHA, Neb. -- Canadian Pacific has issued another report arguing for its proposed takeover of Norfolk Southern, but officials at that railroad promptly criticized it.

Canadian Pacific issued its third report on what it believes would be the benefits of the proposed roughly $30 billion deal on Wednesday morning. This report focused on why Canadian Pacific believes regulators might approve the deal.

Norfolk Southern responded that the report is misleading and its executives concluded regulatory approval is extremely unlikely.

The disagreement over the chances for regulatory approval is a byproduct of the fact that no major railroad mergers have been approved since regulators adopted tough rules for them in 2001.

Norfolk Southern has rejected all of Canadian Pacific's offers, but now CP is trying to make a case for the merger with shareholders.