TD, says it will try to block the merger between freight railroads Union Pacific and Norfolk Southern, citing UP labor practices.

Union Pacific said on Tuesday it would buy smaller rival Norfolk Southern in an $85 billion deal to create the first U.S. coast-to-coast freight rail operator and reshape the movement of goods from grains to autos across the country.

Lawyers from two of Wall Street’s top deals firms are advising on Union Pacific Corp.'s planned $72 billion acquisition of Norfolk Southern Corp.